NEW YORK, NY - AUGUST 28: Viktor Troicki of Serbia returns the ball during his men's singles first round match against Tennys Sandgren of the United States on Day Two of the 2018 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2018 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
