KEY BISCAYNE, FL - MARCH 27: Juan Martin Del Potro of Argentina wipes his towel in his match against Roger Federer of Switzerland at Crandon Park Tennis Center on March 27, 2017 in Key Biscayne, Florida. (Photo by Julian Finney/Getty Images)
KEY BISCAYNE, FL - MARCH 27: Juan Martin Del Potro of Argentina wipes his towel in his match against Roger Federer of Switzerland at Crandon Park Tennis Center on March 27, 2017 in Key Biscayne, Florida. (Photo by Julian Finney/Getty Images)