see more

WASHINGTON, DC - JULY 31: Stan Wawrinka of Switzerland prepares for a shot from Donald Young of the U.S. during Day Four of the Citi Open at the Rock Creek Tennis Center on July 31, 2018 in Washington, DC. (Photo by Mitchell Layton/Getty Images)

WASHINGTON, DC - JULY 31:  Stan Wawrinka of Switzerland prepares for a shot from Donald Young of the U.S. during Day Four of the Citi Open at the Rock Creek Tennis Center on July 31, 2018 in Washington, DC.  (Photo by Mitchell Layton/Getty Images)