NEW YORK, NY - SEPTEMBER 05: Juan Martin del Potro of Argentina returns a shot to against Dominic Thiem of Austria during his fourth round Men's Singles match on Day Eight of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 5, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Al Bello/Getty Images)
