Serbia's Novak Djokovic reacts during his third round round match against Radek Stepanek of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 18, 2013. (AP Photo/Dita Alangkara)

Photo by: Dita Alangkara

Serbia's Novak Djokovic reacts during his third round round match against Radek Stepanek of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 18, 2013. (AP Photo/Dita Alangkara)