Katie Boulter put up a brave fight but was unable to get the better of Elena Rybakina on Sunday as the British women's No. 1 fell to a 6-0, 7-5 third-round defeat at Indian Wells.
Rybakina took just 26 minutes to take a set lead as the former Wimbledon champion won 80% of her points on first serve in California.
However, the momentum shifted in the second set as Rybakina's service game deserted her.
Boulter looked well-placed to level the scores as she served for the second set with a 5-4 lead, but a miraculous backhand return from the Russian-born Kazakhstani seemed to dent the Brit's belief.
The world No. 7 took advantage of Boulter's wobble to overturn the deficit and book her place in the next round.
Elsewhere on Sunday, fellow Brit Cameron Norrie saw his Indian Wells campaign ended by American Tommy Paul.