NEW YORK, USA - SEPTEMBER 11: Novak Djokovic (C) of Serbia is in action against Stan Wawrinka (not seen) of Switzerland during their Men's Singles Final Match on Day Fourteen of the 2016 US Open at the USTA Billie Jean King National Tennis Center New York City, NY, United States on September 11, 2016. Volkan Furuncu / Anadolu Agency