Caroline Wozniacki of Denmark hits a backhand return to Christina McHale of the U.S. during their second round match at the Australian Open tennis championship in Melbourne, Australia, Thursday, Jan. 16, 2014.(AP Photo/Eugene Hoshiko)
Caroline Wozniacki of Denmark hits a forehand return to Christina McHale of the U.S. during their second round match at the Australian Open tennis championship in Melbourne, Australia, Thursday, Jan. 16, 2014.(AP Photo/Aaron Favila)
Maria Sharapova of Russia reacts during her second round match against Karin Knapp of Italy at the Australian Open tennis championship in Melbourne, Australia, Thursday, Jan. 16, 2014.(AP Photo/Aaron Favila)