NEW YORK, NY - SEPTEMBER 06: Roger Federer of Switzerland reacts against Juan Martin del Potro of Argentina during their Men's Singles Quarterfinal match on Day Ten of the 2017 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2017 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
