Britain's Jack Draper reached the last 16 of a Grand Slam for the first time at the US Open but Dan Evans lost a thriller to top seed Carlos Alcaraz.
Draper, 21, continued to brush off a pre-tournament injury with a 6-4 6-2 3-6 6-3 win over American Michael Mmoh.
Evans, 33, went toe-to-toe with defending champion Alcaraz before going down 6-2 6-3 4-6 6-3 in New York.
Cameron Norrie lost 6-3 6-4 6-3 to Italy's Matteo Arnaldi, while Katie Boulter plays later on Saturday.
Like Draper, Boulter is bidding for her best run at a major when she faces American world number 59 Peyton Stearns.