NEW YORK, NY - SEPTEMBER 13:  Novak Djokovic (L) of Serbia celebrates with his coach Boris Becker after defeating Roger Federer of Switzerland during their Men's Singles Final match on Day Fourteen of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 13, 2015 in the Flushing neighborhood of the Queens borough of New York City. Djokovic defeated Federer 6-4, 5-7, 6-4, 6-4.  (Photo by Michael Heiman/Getty Images)