see more

NEW YORK, NY - SEPTEMBER 01: Kei Nishikori of Japan returns the ball during the men's singles third round match against Diego Schwartzman of Argentina on Day Six of the 2018 US Open at the USTA Billie Jean King National Tennis Center on September 1, 2018 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Steven Ryan/Getty Images)

NEW YORK, NY - SEPTEMBER 01:  Kei Nishikori of Japan returns the ball during the men's singles third round match against Diego Schwartzman of Argentina on Day Six of the 2018 US Open at the USTA Billie Jean King National Tennis Center on September 1, 2018 in the Flushing neighborhood of the Queens borough of New York City.  (Photo by Steven Ryan/Getty Images)