Britain's Katie Boulter and Cameron Norrie were knocked out of Indian Wells as they suffered straight-set defeats in the third round.
British women's number one Boulter was beaten 6-0 7-5 by seventh seed Elena Rybakina in California.
British men's number two Norrie earlier lost 6-3 7-5 to 10th seed Tommy Paul.
Sonay Kartal is the only remaining Briton in the women's draw and Jack Draper the last British male.
Playing her first tournament since January's Australian Open because of a foot injury, Boulter received a first-round bye as the 25th seed.
Former Wimbledon champion Rybakina won the first seven games in taking the first set in 26 minutes, but Boulter regrouped in the second and broke Kazakhstan's Rybakina to claim a 4-3 lead before serving for the set at 5-4.
Although Boulter saved two break points, Rybakina took advantage of a third to level it up and, after holding serve, broke Boulter thanks to a double fault on match point.
Rybakina will face Russian ninth seed Mirra Andreeva, who beat Denmark's Clara Tauson 6-3 6-0, in the last 16.
Defending champion Iga Swiatek - chasing a third title in this tournament - dominated Ukraine's Dayana Yastremska 6-0 6-2.
Poland's Swiatek will play Karolina Muchova, a 7-5 6-1 winner against fellow Czech Katerina Siniakova, next.
American fourth seed Jessica Pegula beat China's Wang Xinyu 6-2 6-1 to set up a meeting with Ukrainian Elina Svitolina, who beat American Danielle Collins 6-2 6-4.
World number 77 Norrie, who claimed his biggest career title by winning Indian Wells in 2021, was broken three times before handing American Paul the opening set with a double fault.
In the second set Norrie was broken again before levelling at 4-4, but served a fifth double fault on match point.
World number 11 Paul, who will play Russian fifth seed Daniil Medvedev in the last 16, said: "It was a super weird match - a lot of breaks. It was an up-and-down match on both sides."
Draper, the 13th seed, will play American Jenson Brooksby on Monday.
Medvedev progressed as American Alex Michelsen retired after two games because of illness, while Greece's Stefanos Tsitsipas beat Italian Matteo Berrettini 6-3 6-3.