Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic hits a forehand return to Serbia's Novak Djokovic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic hits a backhand return to Serbia's Novak Djokovic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic wipes his face during a break in his fourth round match against Canada's Milos Raonic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic leaps a signboard as he attempts to hit a return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic hits a forehand return to Serbia's Novak Djokovic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic hits a backhand return to Serbia's Novak Djokovic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic reacts during his fourth round match against Canada's Milos Raonic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic has his ankle strapped during his fourth round match against Serbia's Novak Djokovic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic reacts during his fourth round match against Canada's Milos Raonic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic reacts during his fourth round match against Canada's Milos Raonic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

United States' Serena Williams falls during her fourth round match against Aryna Sabalenka of Belarus at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair), APTOPIX

Aryna Sabalenka of Belarus throws her racket in frustration during her fourth round match against United States' Serena Williams at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair), APTOPIX

Romania's Simona Halep hits a backhand return to Poland's Iga Swiatek during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair), APTOPIX

Austria's Dominic Thiem serves to Buglaria's Grigor Dimitrov during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair), APTOPIX

Buglaria's Grigor Dimitrov hits a backhand return to Austria's Dominic Thiem during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair), APTOPIX

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a backhand return to Canada's Milos Raonic during their fourth round match on Rod Laver Arena at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Canada's Milos Raonic reacts during his fourth round match against Serbia's Novak Djokovic at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic celebrates after defeating Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic celebrates after defeating Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic celebrates after defeating Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic reacts after defeating Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic, left, is congratulated by Canada's Milos Raonic after winning their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic hits a forehand return to Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic celebrates after defeating Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic reacts after winning a point against Canada's Milos Raonic during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Feb. 15, 2021.(AP Photo/Hamish Blair)

Serbia's Novak Djokovic wipes the sweat from his face during his fourth round match against Canada's Milos Raonic at the Australian Open tennis championship in Melbourne, Australia, Sunday, Feb. 14, 2021.(AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic and compatriot Karolina Pliskova play in an empty Rod Laver Arena during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic and compatriot Karolina Pliskova play in an empty Rod Laver Arena during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.(AP Photo/Andy Brownbill)

An empty Garden Square is seen at Melbourne Park, venue for the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic and compatriot Karolina Pliskova play in an empty Rod Laver Arena during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.(AP Photo/Andy Brownbill)

An empty Garden Square is seen at Melbourne Park, venue for the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic plays a backhand return to compatriot Karolina Muchova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic plays a backhand return to compatriot Karolina Muchova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic plays a forehand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic plays a forehand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Kazakhstan's Yulia Putintseva hits a backhand to Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Kazakhstan's Yulia Putintseva hits a forehand to Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic reacts during her third round match against compatriot Karolina Pliskova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic reacts during her third round match against compatriot Karolina Pliskova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic reacts during her third round match against compatriot Karolina Pliskova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina celebrates a point against Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Kazakhstan's Yulia Putintseva looks up while playing Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Karolina Pliskova of the Czech Republic throws her racket in frustration during her third round match against compatriot Karolina Muchova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic throws her racket in frustration during her third round match against compatriot Karolina Muchova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic throws her racket in frustration during her third round match against compatriot Karolina Muchova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic reacts during her third round match against compatriot Karolina Muchova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic serves to compatriot Karolina Muchova during her third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic throws her racket in frustration during her third round match against compatriot Karolina Muchova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina, top, serves to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic serves to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic serves to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic hits a backhand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Kazakhstan's Yulia Putintseva, left, serves to Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic hits a backhand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic serves to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Ukraine's Elina Svitolina, left, plays Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic wipes the sweat from her face during her third round match against compatriot Karolina Pliskova at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic hits a backhand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic hits a backhand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Karolina Muchova of the Czech Republic hits a backhand return to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Muchova of the Czech Republic reacts after losing a point to compatriot Karolina Pliskova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Kazakhstan's Yulia Putintseva hits a forehand to Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina hits a forehand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Karolina Pliskova of the Czech Republic hits a forehand return to compatriot Karolina Muchova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Karolina Pliskova of the Czech Republic serves to compatriot Karolina Muchova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Moldova's Radu Albot hits a backhand return to Norway's Casper Ruud during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Moldova's Radu Albot hits a forehand return to Norway's Casper Ruud during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a backhand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a backhand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud serves to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

France's Kristina Mladenovic serves to United States' Jessica Pegula France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

France's Kristina Mladenovic serves to United States' Jessica Pegula France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Norway's Casper Ruud hits a backhand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

France's Kristina Mladenovic hits a backhand to United States' Jessica Pegula France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Norway's Casper Ruud hits a backhand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a backhand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Jessica Pegula hits a forehand to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula hits a backhand to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Norway's Casper Ruud reacts during his third round match against Moldova's Radu Albot at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Jessica Pegula hits a forehand to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Norway's Casper Ruud hits a forehand return to Moldova's Radu Albot during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula hits a forehand to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula celebrates a point against France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula shakes hands with France's Kristina Mladenovic follwong her win in their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

France's Kristina Mladenovic opens her arms after a shot to United States' Jessica Pegula during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

France's Kristina Mladenovic hits a backhand to United States' Jessica Pegula during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

France's Kristina Mladenovic hits a forehand to United States' Jessica Pegula during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

South Africa's Lloyd Harris serves to United States' Mackenzie McDonald during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

South Africa's Lloyd Harris hits a forehand return to United States' Mackenzie McDonald during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

South Africa's Lloyd Harris hits a backhand return to United States' Mackenzie McDonald during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

United States' Jessica Pegula, top, plays France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

United States' Mackenzie McDonald, left, hits a backhand return to South Africa's Lloyd Harris during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Mackenzie McDonald hits a forehand return to South Africa's Lloyd Harris during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Mackenzie McDonald hits a backhand return to South Africa's Lloyd Harris during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

South Africa's Lloyd Harris hits a backhand return to United States' Mackenzie McDonald during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

United States' Mackenzie McDonald hits a backhand return to South Africa's Lloyd Harris during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Estonia's Kaia Kanepi Croatia's hits a backhand to Donna Vekic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Estonia's Kaia Kanepi hits a backhand to Croatia's Donna Vekic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)