MASON, OH - AUGUST 16: Mitchell Krueger returns s shot to Juan Martin Del Potro of Argentina during day 5 of the Western & Southern Open at the Lindner Family Tennis Center on August 15, 2017 in Mason, Ohio. (Photo by Matthew Stockman/Getty Images)
MASON, OH - AUGUST 16: Mitchell Krueger returns s shot to Juan Martin Del Potro of Argentina during day 5 of the Western & Southern Open at the Lindner Family Tennis Center on August 15, 2017 in Mason, Ohio. (Photo by Matthew Stockman/Getty Images)