David Ferrer of Spain celebrates after winning over Jeremy Chardy of France during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
Dominika Cibulkova of Slovakia celebrates a point won against Maria Sharapova of Russia during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 20, 2014.(AP Photo/Aaron Favila)
Lucie Safarova of the Czech Republic hits a backhand return to Li Na of China during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Rick Rycroft)
Li Na of China appeals a point as she plays Lucie Safarova of the Czech Republic during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Rick Rycroft)
David Ferrer of Spain changes his shirt during his third round match against Jeremy Chardy of France at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
David Ferrer of Spain plays a shot to Jeremy Chardy of France during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
Serena Williams of the U.S. makes a backhand return to Daniela Hantuchova of Slovakia during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
Serena Williams of the U.S. cools down with ice towel on her shoulders between games during her third round match against Daniela Hantuchova of Slovakia at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014. (AP Photo/Aaron Favila)
Florian Mayer of Germany makes a forehand return to Jerzy Janowicz of Poland during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014. (AP Photo/Shuji Kajiyama)
Serena Williams of the U.S. celebrates after defeating Daniela Hantuchova of Slovakia in their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
Angelique Kerber, left, of Germany is congratulated by Alison Riske of the U.S. during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Rick Rycroft)
Serena Williams of the U.S. serves to Daniela Hantuchova of Slovakia during their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)
Serena Williams of the U.S. takes a drink during a break in her third round match against Daniela Hantuchova of Slovakia at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 17, 2014.(AP Photo/Aaron Favila)