Novak Djokovic of Serbia returns the ball to Denis Istomin of Uzbekistan during their men's singles match at the Dubai Tennis Championships, February 25, 2014. REUTERS/Faisal Al Nasser (UNITED ARAB ... more 
Novak Djokovic of Serbia returns the ball to Denis Istomin of Uzbekistan during their men's singles match at the Dubai Tennis Championships, February 25, 2014. REUTERS/Faisal Al Nasser (UNITED ARAB EMIRATES - Tags: SPORT TENNIS) less 
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Reuters | Photo By FAISAL AL NASSER / REUTERS
Tue, Feb 25, 2014 11:44 AM EST