NEW YORK, NY - SEPTEMBER 04: Elise Mertens of Belgium in action during her girls' singles second round match against Katie Boulter of Great Britain on Day Ten of the 2013 US Open at USTA Billie Jean King National Tennis Center on September 4, 2013 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)
