Elena Baltacha's hopes of becoming the first British woman since 1992 to reach round three of the French Open ended with defeat by American Vania King.
Baltacha, 27, was bidding to match the feat of Jo Durie 19 years ago but lost 4-6 6-1 6-4 in two hours, five minutes.
The British number one, ranked 83rd in the world, dominated world number 115 King in the opening set, only to lose nine of the subsequent 11 games.
She rallied late on but King prevailed to set up a meeting with Petra Kvitova.
"I knew that going into the match that it was going to be very difficult," said Baltahca. "She's got a good game on clay and she's playing very well.
"I was able to dominate in the first set, then maybe went a bit flat in the second and in the third, even though I was more aggressive, she was just absorbing my pace and I wasn't really able to get her out of court.
"That's really the big reason why I lost the match today.
"I'm not beating myself up. There are a lot of positives and I can go away from here proud of what I've done."
Baltacha and King were meeting for the first time after the Briton beat Sloane Stephens and the American shocked 22nd seed Dominika Cibulkova.
Attempting to make it to the third round of a Grand Slam for only the second time, King got off off to the stronger start with a gritty hold and a confident break of serve made it 2-0.
The 22-year-old's backhand drop shots troubled Baltacha in the first two games, but the Scot swiftly figured her opponent out and hit straight back to love.
She now had the momentum and saved two break points to level at 2-2 before fighting back from 40-15 to strike again in game five.
After holding for 3-4, King upped the intensity and engineered two break points - but Baltacha dug deep to save both and move to within a game of the set.
She wrapped it up in game 10 on her fourth set point, finishing with 15 winners to her opponent's 12 and nine unforced errors to King's 13.
With one foot in the third round, Baltacha went in for the kill at the start of the second set and had three chances to break in game one.
Yet King stood firm under intense pressure and that proved the turning point.
The California-based right-hander took advantage of Baltacha's faltering serve to break for 2-0 and held comfortably in game three.
She then secured the double-break in game four as Baltacha's first-serve percentage plummeted to around 50% and her error count started to rise.
Both players managed to hold in games five and six but King served out with ease to level the match and force a decider.
Nerves were palpable in a 13-minute opening game in which Baltacha resorted to 'moonballing' - and she was punished as King snapped up an early break.
Things went from bad to worse for the Ipswich-based right-hander when she was taken apart in game three, a break to love meaning she had lost nine out of the last 10 games.
Baltacha was unwilling to go down without a fight and responded with her own break to love, but King immediately restored her advantage when the Briton put a forehand wide.
With both players struggling for consistency, Baltacha was able to notch a second successive break in game six and three service holds followed to keep her hopes alive.
But King kept cool to bring up match point at 5-4 and took it when Baltacha floated a forehand beyond the baseline.
Baltacha can switch her attention to the grass-court stretch of the season and is scheduled to compete in Birmingham and Eastbourne in the build-up to Wimbledon.
"I've learned so much about my game, how much I've developed and I've used tactics and things that I've never really kind of had the confidence to experiment with before in matches," she added.
"I have done that on the clay, and I think my game has really improved in this area."
"I've learned a lot, I've picked up a lot of points and I'm going into the grass ready to really enjoy it and try and make the most of it."
King will next play highly-fancied ninth seed Kvitova after the Czech player saw off China's Jie Zheng 6-4 6-1.