Victoria Azarenka did damage to her racket but failed to have much of an impact on her opponent.
The No. 1 seed at the French Open fell 6-2, 7-6 (4) to 15th-seeded Dominika Cibulkova on a windy, gray day at Roland Garros where the world's top-ranked player hardly looked the part.
Azarenka, who won the Australian Open to start the 2012 Grand Slam season, pulled out a first game that went nine deuces and took 15 minutes but didn't capture any momentum in the process.
Her frustration was still showing after the match, when, asked what she would do to recover from the loss, she answered sarcastically.
"I'm going to kill myself," she said. "This tournament is over for me. What's to recover from? It's (time) to really look forward and improve. That's it."
Cublkova will face U.S. Open champion Sam Stosur, who ended unseeded American teenager Sloan Stephens' best run at a Grand Slam with a 7-5, 6-4 victory.
The 19-year-old Stephens, of Coral Springs, Fla., fell behind 5-1 in the second set before breaking Stosur twice to extend things. But the Australian broke Stephens to end it.
Stephens' exit leaves Varvara Lepchenko, who's also unseeded, as the only U.S. singles player left in the tournament. Lepchenko takes on Wimbledon champion Petra Kvitova of the Czech Republic in the fourth round Monday.
Down 6-3 in the second-set tiebreaker, Azarenka saved one match point. But on the second, Cibulkova drew her to the net with a drop shot, then passed her easily for the winner. The Slovakian dropped onto the red clay to celebrate. She had taken Azarenka to three sets the last five times they played, but her only victory in that streak came in 2008 at Amelia Island - the last time they met on clay.
"Before, I was at least making something happen myself," Azarenka said, when asked about those previous three-setters. "Today I couldn't do it. All I could hope for is for her mistake. I couldn't make anything myself today."
Azarenka joins a large group of so-called favorites on the sidelines. The Williams sisters, former No. 1 Caroline Wozniacki and former champions Ana Ivanovic and Francesca Schiavone are among those already gone with the second week just getting under way.
Another former champion, Svetlana Kuznetsova, lost Sunday to 21st-seeded Sara Errani of Italy.
Five women have won the last five Grand Slam titles and the last four majors have been won by first-time champions. The only former champion left in the draw is Li Na.
"I'm happy and curious," said Errani, now in her second straight Grand Slam quarterfinal. "The strongest sensation is curiosity - to see how far I can go, and up to what level I can arrive. Even I don't really know."
Errani's next opponent is 10th-seeded Angelique Kerber, a 6-3, 7-5 winner over Petra Martic. Kerber had only one victory in her previous four appearances at Roland Garros. She now finds herself two wins away from playing for the title.
"It's a new situation," Kerber said. "I've played good from the beginning of the year. I think the players know right now who I am, and, yeah, I think nobody wants to play against me right now."