Australian Open

Williams of the U.S. serves during her quarter-final match against Russia's Sharapova at the Australian Open tennis tournament at Melbourne Park...Serena Williams of the U.S. serves during her quarter-final match against Russia's Maria Sharapova at the Australian Open tennis tournament at Melbourne Park, Australia, January 26, 2016. REUTERS/Thomas Peter       TPX IMAGES OF THE DAY

Thomas Peter/Reuters

Serena Williams of the U.S. serves during her quarter-final match against Russia’s Maria Sharapova at the Australian Open tennis tournament at Melbourne Park, Australia

Novak Djokovic of Serbia prepares to serve to  Andreas Seppi of Italy during their third round match at the Australian Open tennis championships in Melbourne, Australia, Friday, Jan. 22, 2016.(AP Photo/Andrew Brownbill)

Andrew Brownbill/AP

Novak Djokovic of Serbia prepares to serve to Andreas Seppi of Italy during their third round match at the Australian Open tennis championships in Melbourne, Australia

Canada's Raonic signs autographs after winning his second round match against Spain's Robredo at the Australian Open tennis tournament at Melbourne Park...Canada's Milos Raonic signs autographs after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato

Issei Kato/Reuters

Canada’s Milos Raonic signs autographs after winning his second round match against Spain’s Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia 

Germany's Brown plays during his doubles match at the Australian Open tennis tournament at Melbourne Park...Germany's Dustin Brown plays during his doubles match at the Australian Open tennis tournament at Melbourne Park, Australia, January 20, 2016. REUTERS/Jason O'Brien

Jason O'Brien/Reuters

Germany’s Dustin Brown plays during his doubles match at the Australian Open tennis tournament at Melbourne Park, Australia

Jason Reed/Reuters

Serbia’s Novak Djokovic serves during his first round match against South Korea’s Hyeon Chung at the Australian Open tennis tournament at Melbourne Park, Australia 

Grigor Dimitrov of Bulgaria is silhouetted as he plays Rafael Nadal of Spain during their quarterfinal at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 22, 2014.

Aijaz Rahi/AP

Grigor Dimitrov of Bulgaria is silhouetted as he plays Rafael Nadal of Spain during their quarter final at the Australian Open tennis championship in Melbourne, Australia

Serena Williams of the U.S. serves to Daniela Hantuchova of Slovakia during their women's singles match at the Australian Open 2014 tennis tournament in Melbourne...Serena Williams of the U.S. serves to Daniela Hantuchova of Slovakia during their women's singles match at the Australian Open 2014 tennis tournament in Melbourne January 17, 2014.

Jason Reed/Reuters

Serena Williams of the US serves to Daniela Hantuchova of Slovakia during their women’s singles match at the Australian Open 2014 tennis tournament in Melbourne. Williams won 6-3 6-3. 

Tennis fans protect themselves from the sun during a first round match at the Australian Open tennis championship in Melbourne, Australia, Tuesday, Jan. 14, 2014.

Aaron Favila/AP

Tennis fans protect themselves from the sun during a first round match at the Australian Open tennis championship in Melbourne, Australia