In this photo released by Tennis Australia, Denmark's Caroline Wozniacki smiles as she signs her autograph for fans at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 13, 2014. (AP Photo/Tennis Australia,Fiona Hamilton)

In this photo released by Tennis Australia, Denmark's Caroline Wozniacki shows her new engagement ring as she signs her autograph for fans at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 13, 2014. Wozniacki recently announced her engagement to Northern Ireland golfer Rory McIlroy. (AP Photo/Tennis Australia,Fiona Hamilton)

In this photo released by Tennis Australia, Denmark's Caroline Wozniacki signs her autograph for a young fan at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 13, 2014. (AP Photo/Tennis Australia,Fiona Hamilton)