Novak Djokovic of Serbia kisses the trophy during the award ceremony after defeating Rafael Nadal of Spain in the men's singles final at the Australian Open tennis championship, in Melbourne, Australia, early Monday, Jan. 30, 2012. (AP Photo/Rick Rycroft)
Novak Djokovic of Serbia serves to Rafael Nadal of Spain during the men's singles final at the Australian Open tennis championship in Melbourne, Australia, on Sunday, Jan. 29, 2012. (AP Photo/John Donegan)
Victoria Azarenka of Belarus kisses the trophy during the awarding ceremony after defeating Maria Sharapova of Russia in their women's singles final at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 28, 2012. (AP Photo/Rick Rycroft)
Novak Djokovic of Serbia celebrates after defeating Andy Murray of Britain during their semifinal at the Australian Open, in Melbourne, Australia, early Saturday, Jan. 28, 2012. (AP Photo/Andrew Brownbill)
Rafael Nadal (left) celebrates a point win against Roger Federer during their semifinal Jan. 26, 2012, at the Australian Open in Melbourne, Australia. (Associated Press)
David Ferrer chases down a ball during his quarterfinal loss to Novak Djokovic at the Australian Open. Djokovic next will play Andy Murray in a rematch of last year's final. (Associated Press)
Rafael Nadal celebrates during his quarterfinal against Tomas Berdych at the Australian Open tennis championship, in Melbourne, Australia, Tuesday, Jan. 24, 2012. (AP Photo/Vivek Prakash,Pool)
Serena Williams bounces her racket Jan. 23, 2012, during her fourth-round match against Ekaterina Makarova at the Australian Open in Melbourne, Australia. (Associated Press)
Serena Williams of the U.S. reacts in frustration during her fourth-round match against Russia's Ekaterina Makarova at the Australian Open in Melbourne, Australia, on Monday, Jan. 23, 2012. (AP Photo/Andrew Brownbill)
Serbia's Novak Djokovic celebrates following his win over France's Nicholas Mahut in their third-round match at the Australian Open, in Melbourne, Australia, Saturday, Jan. 21, 2012. (AP Photo/John Donegan)
Serena Williams celebrates after defeating Greta Arn during their third-round match at the Australian Open, in Melbourne, Australia, Saturday, Jan. 21, 2012. (AP Photo/Andrew Brownbill)
John Isner of the US lost to Spain's Feliciano Lopez at the Australian Open in Melbourne, Australia, 6-3, 6-7 (3), 6-4, 6-7 (0), 6-1. (AP Photo/Rick Rycroft)
Victoria Azarenka celebrates after defeating Mona Barthel during their third-round match at the Australian Open, in Melbourne, Australia, Friday, Jan. 20, 2012. (AP Photo/Rick Rycroft)
Andy Roddick of the U.S. reaches for a forehand return to Australia's Lleyton Hewitt during their second round match at the Australian Open tennis championship, in Melbourne, Australia, Thursday, Jan. 19, 2012. (AP Photo/John Donegan)
Maria Sharapova waves to the crowd after beating Jamie Hampton during their second-round match at the Australian Open in Melbourne, Australia, Thursday, Jan. 19, 2012. (AP Photo/John Donegan)
Caroline Wozniacki waves to the crowd after beating Anna Tatishvili during their second-round match at the Australian Open, in Melbourne, Australia, Wednesday, Jan. 18, 2012. (AP Photo/Rick Rycroft)
Spain's Rafael Nadal makes a backhand return to Germany's Tommy Haas during their second round match at the Australian Open tennis championship, in Melbourne, Australia, Wednesday, Jan. 18, 2012. (AP Photo/Andrew Brownbill)
Li Na of China returns a ball to Australia's Olivia Rogowska during their second round match at the Australian Open tennis championship, in Melbourne, Australia, Wednesday, Jan. 18, 2012. (AP Photo/Andrew Brownbill)
Spain's Rafael Nadal makes a backhand return to Alex Kuznetsov of the U.S. during their first round match at the Australian Open tennis championship, in Melbourne, Australia, Monday, Jan. 16, 2012. (AP Photo/Rick Rycroft)
Rafael Nadal makes a forehand return to Alex Kuznetsov during their first-round match Jan. 16, 2012, at the Australian Open in Melbourne, Australia. (Associated Press)