NEW YORK, NY - AUGUST 28:  John Isner of the United States serves against Jan-Lennard Struff of Germany during their men's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014 in the Flushing neighborhood of the Queens borough of New York City.  (Photo by Streeter Lecka/Getty Images)