Roger Federer of Switzerland celebrates after defeating Andy Murray of Britain during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Rick Rycroft)
Roger Federer of Switzerland waves after defeating Andy Murray of Britain in their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014. (AP Photo/Aaron Favila)
Victoria Azarenka of Belarus speaks during a press conference after her quarterfinal loss to Agnieszka Radwanska of Poland at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014. (AP Photo/Shuji Kajiyama)
Victoria Azarenka of Belarus bites a towel during a break in her quarterfinal against Agnieszka Radwanska of Poland at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Andrew Brownbill)
Grigor Dimitrov of Bulgaria lies on the court between points as he plays Rafael Nadal of Spain during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014. (AP Photo/Aijaz Rahi)
Rafael Nadal of Spain celebrates after defeating Grigor Dimitrov of Bulgaria during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Eugene Hoshiko)
Andy Murray of Britain adjusts his cap as he plays Roger Federer of Switzerland during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Andrew Brownbill)
Rafael Nadal of Spain walks off the court after defeating Grigor Dimitrov of Bulgaria in their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Aaron Favila)
Roger Federer of Switzerland throws a towel as he plays Andy Murray of Britain during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Rick Rycroft)
Roger Federer of Switzerland, right, is congratulated by Andy Murray of Britain at the net after Federer won their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Andrew Brownbill)
Andy Murray of Britain reacts after losing a point to Roger Federer of Switzerland during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Eugene Hoshiko)
Andy Murray of Britain reacts after losing a point to Roger Federer of Switzerland during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Rick Rycroft)
Andy Murray of Britain speaks during a press conference after his quarterfinal loss to Roger Federer of Switzerland at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014. (AP Photo/Aijaz Rahi)
Rafael Nadal of Spain walks off the court after defeating Grigor Dimitrov of Bulgaria in their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.(AP Photo/Aaron Favila)