Novak Djokovic of Serbia, left, shakes hands with Gilles Muller of Luxembourg after winning their fourth round match at the Australian Open tennis championship in Melbourne, Australia, early Tuesday, ... more 
Novak Djokovic of Serbia, left, shakes hands with Gilles Muller of Luxembourg after winning their fourth round match at the Australian Open tennis championship in Melbourne, Australia, early Tuesday, Jan. 27, 2015. (AP Photo/Rob Griffith) less 
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Associated Press | Photo By Rob Griffith
Mon, Jan 26, 2015 8:27 AM EST