The 38-year-old had hoped to retire at an ATP Tour event, but could not get a main-draw wild card in Florence or Naples.

The Aussie was struck in the eye by a tennis ball in Acapulco and is still experiencing vision problems. 

Millman is vaccinated, but he is not eager to have other players excluded from the event.

"It's never easy playing against a really close friend," the fifth seed said Thursday.

For this clash between the Aussie and American we are looking for a certain player to capture the first set only. 

Coming into this week, the big story was Rafael Nadal’s first trip to Washington, D.C. Now the big story is Jenson Brooksby’s trip to the final four, following his 6-1, 6-2 dismissal of John Millman on Friday.

Aslan Karatsev's recent run, and those of others, shows it's never too late to break out.

Fourth-seeded Andrey Rublev eased past American Marcos Giron, 7-6 (1), 6-3, after 79 minutes, while countryman Karen Khachanov upstaged 2015 champion Stan Wawrinka, 6-4, 7-5, on Tuesday at the ABN AMRO World Tennis Tournament.