NEW YORK, NY - AUGUST 31:  Kei Nishikori of Japan walks off of the court after losing against Benoit Paire of France during their Men's Single First Round match on Day One of the 2015 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2015 in the Flushing neighborhood of the Queens borough of New York City.  (Photo by Streeter Lecka/Getty Images)