Australian Open tennis championship defending women's singles champion Victoria Azarenka of Belarus, right, and men's singles defending champion Novak Djokovic of Serbia place their trophies on a stand at the official draw for the 2013 event in Melbourne, Australia, Friday, Jan. 11, 2013. (AP Photo/Fiona Hamilton)

Britain's Andy Murray serves as coach Ivan Lendl looks on during a practice session at Melbourne Park as he prepares for next week's Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 11, 2013. (AP Photo/Andy Wong)

Serbia's Janko Tipsarevic reacts during his first round match against Australia's Lleyton Hewitt at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 14, 2013. (AP Photo/Aaron Favila)

Serbia's Janko Tipsarevic returns to Australia's Lleyton Hewitt in their first round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 14, 2013. (AP Photo/Andrew Brownbill)

Serbia's Janko Tipsarevic reacts after winning a point against Australia's Lleyton Hewitt in their first round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 14, 2013. (AP Photo/Andrew Brownbill)

Australia's Lleyton Hewitt reacts during his first round match against Serbia's Janko Tipsarevic at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 14, 2013. (AP Photo/Andrew Brownbill)

Venus Williams of the US waves after defeating Kazakstan's Galina Voskoboeva during their first round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 14, 2013. (AP Photo/Rob Griffith)

Switzerland's Roger Federer answers questions at a press conference following his loss to Britain's Andy Murray in their semifinal at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 26, 2013. (AP Photo/Andrew Brownbill)

Switzerland's Roger Federer waves to the crowd after losing his semifinal match against Britain's Andy Murray at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 25, 2013. (AP Photo/Andy Wong)

Switzerland's Roger Federer answers questions at a press conference following his loss to Britain's Andy Murray in their semifinal at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 26, 2013. (AP Photo/Andrew Brownbill)

Mirka Federer reacts during the final set in the semifinal match between her husband Roger Federer and Britain's Andy Murray at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 25, 2013. (AP Photo/Andy Wong)