WASHINGTON, DC - JULY 21: Sam Querrey of the United States of America serves to Alexandr Dolgopolov of Ukraine during day 4 of the Citi Open at Rock Creek Tennis Center on July 21, 2016 in Washington, DC. (Photo by Matt Hazlett/Getty Images)
WASHINGTON, DC - JULY 21: Sam Querrey of the United States of America serves to Alexandr Dolgopolov of Ukraine during day 4 of the Citi Open at Rock Creek Tennis Center on July 21, 2016 in Washington, DC. (Photo by Matt Hazlett/Getty Images)