Novak Djokovic of Serbia reacts to a point lost to Andy Murray of Britain during their ATP World Tour Finals singles tennis match at the O2 Arena in London, Wednesday, Nov. 7, 2012. (AP Photo/Sang ... more 
Novak Djokovic of Serbia reacts to a point lost to Andy Murray of Britain during their ATP World Tour Finals singles tennis match at the O2 Arena in London, Wednesday, Nov. 7, 2012. (AP Photo/Sang Tan) less 
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Associated Press | Photo By Sang Tan
Wed, Nov 7, 2012 12:55 PM EST