British number one Johanna Konta has been knocked out of the US Open in the last 16 by Anastasija Sevastova.
The 13th seed lost 6-4 7-5 against the Latvian world number 48.
Konta fought back to 5-5 from 4-1 down in the second set and saved two match points, but was finally undone as Sevastova broke serve to win.
Sevastova, who retired in 2013 before making a comeback, will play Caroline Wozniacki in the quarter-finals.
Konta was bidding to become the first British woman in the quarter-finals in New York since Jo Durie in 1983.
She said: “I didn’t play the tennis level that I maybe would have liked, but I competed the best I could.
“Right now I’m pretty tired,” Konta told BBC Sport. “It is a very long season with the Olympics thrown in the mix.
“It was challenging but equally rewarding – it was a great experience to be part of Team GB.
“I’ve played a lot of very good matches and won a lot of them, so it’s a good problem to have.”
German second seed Angelique Kerber beat two-time Wimbledon champion Petra Kvitova 6-3 7-5 to keep alive her bid to become world number one.
The result means Serena Williams will have to reach the final and, if it’s against Kerber, win the tournament to prevent the Australian Open winner taking top spot in the rankings.
Kerber will play Italian seventh seed Roberta Vinci for a place in the semi-finals. Vinci, the 2015 runner-up, overcame Lesia Tsurenko of Ukraine 7-6 (7-5) 6-2.