WASHINGTON, DC - JULY 30: Mackenzie McDonald returns a backhand to Andy Murray during the Citi Open at the Rock Creek Tennis Center on July 30, 2018 in Washington, DC. (Photo by Mitchell Layton/Getty Images)
WASHINGTON, DC - JULY 30: Mackenzie McDonald returns a backhand to Andy Murray during the Citi Open at the Rock Creek Tennis Center on July 30, 2018 in Washington, DC. (Photo by Mitchell Layton/Getty Images)