NEW YORK, NY - AUGUST 24: Novak Djokovic participates in skills challenge during the 2013 Arthur Ashe Kids Day at USTA Billie Jean King National Tennis Center on August 24, 2013 in the Queens borough ... more 
NEW YORK, NY - AUGUST 24: Novak Djokovic participates in skills challenge during the 2013 Arthur Ashe Kids Day at USTA Billie Jean King National Tennis Center on August 24, 2013 in the Queens borough of New York City. (Photo by Robin Marchant/Getty Images) less 
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Getty Images | Photo By Robin Marchant / Getty Images
Sat, Aug 24, 2013 11:23 PM EDT