Britain’s Jack Draper’s run at Flushing Meadows was ended by Russian eighth seed Andrey Rublev.
Wimbledon champion Martketa Vodrousova is through to the quarter-finals and will face Madison Keys.
But Ons Jabeur, last year’s runner-up, bowed out 6-2 6-4 to China’s Qinwen Zheng, who will play new world number one Aryna Sabalenka.
Here, the PA news agency looks back at day eight at the US Open.
Pic of the day
Match of the day
Wimbledon champion Marketa Vondrousova moved a step closer to back-to-back grand slam titles by beating Peyton Stearns to quarter-finals.
The 24-year-old Czech, seeded ninth here two months after becoming the first unseeded woman to win at SW19, fell a set behind to Stearns.
But the American youngster, whose powerful forehand accounted for Britain’s Katie Boulter in round three, won just five more games as Vondrousova triumphed 6-7 (3) 6-3 6-2.
Jack Draper’s breakthrough run came to an end in the fourth round after a four-set defeat by Russian Rublev.
The British number four, in the second week of a grand slam for the first time, fell 6-3 3-6 6-3 6-4
But Draper’s performances this week will hopefully point to an upward curve in such a promising career hindered by fitness issues.
Stat of the day
Forty and counting…
Quote of the day
Women: Jessica Pegula (3), Ons Jabeur (5), Daria Kasatkina (13).Men: Alex De Minaur (13).
Who’s up next?
The quarter-finals begin with Coco Gauff taking on Iga Swiatek’s conqueror Jelena Ostapenko. Novak Djokovic follows against Taylor Fritz, while in the night session there is an all-American showdown to savour between Frances Tiafoe and Ben Shelton.