Lady Gaga performs at the MTV Video Music Awards at Barclays Center on Sunday, Aug. 25, 2013, in the Brooklyn borough of New York. (Photo by John Shearer/Invision for MTV/AP Images)

Lady Gaga performs "Applause" at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Charles Sykes/Invision/AP)

Lady Gaga onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

Lady Gaga onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

Lady Gaga onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

Lady Gaga onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

Lady Gaga performs "Applause" at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Charles Sykes/Invision/AP)

Lady Gaga, center, performs at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Scott Gries/Invision/AP)

Miley Cyrus performs at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Charles Sykes/Invision/AP)

Miley Cyrus performs at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Charles Sykes/Invision/AP)

Robin Thicke and Miley Cyrus perform at the MTV Video Music Awards on Sunday, Aug. 25, 2013, at the Barclays Center in the Brooklyn borough of New York. (Photo by Scott Gries/Invision/AP)

Miley Cyrus onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

Miley Cyrus and Robin Thicke onstage during the 2013 MTV Video Music Awards at the Barclay Center on Sunday, Aug. 25, 2013 in New York. (Photo by Frank Micelotta/Invision/AP)

RITA ORA @ SOUND OF CHANGE CONCERT- CHIME FOR CHANGE -TWICKENHAM STADIUM, TWICKENHAM , LONDON, U.K.- 1/6/13 PHOTOGRAPH BY: ANGELA LUBRANO / LIVEPIX- DALLE

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Katy Perry performing at MuchMusic Video Awards in Toronto, Sunday, June 20, 2010. (Photo by iPhotoLive.com)/face to face - Germany, Austria, Switzerland, France and Eastern European rights only -

Concert of US singer Britney Spears

Britney Spears performs on a stage during a concert in Moscow, Russia, Saturday, Sept. 24, 2011. Britney Spears performs in Moscow, St.Petersburg and Kiev as part of her European tour. (AP Photo)

Concert of Rihanna in Paris Bercy

Concert of Rihanna in Paris Bercy