World number two Kim Clijsters crashed out of the French Open with a shock second-round defeat by Arantxa Rus.
Playing her first event since March because of injury, the 27-year-old Belgian lost 3-6 7-5 6-1.
Clijsters, a two-time runner-up, wasted two match points in the second set as her 114th-ranked Dutch opponent rallied to seal a meeting with Maria Kirilenko.
Elsewhere, Maria Sharapova recovered from a set and 1-4 down to beat French wildcard Caroline Garcia 3-6 6-4 6-0.
But the story of the day was the shock exit of Clijsters who, despite her lack of practice on clay ahead of Roland Garros, did not regret appearing in this year's tournament.
"I had practised well. Physically everything was fine. I was definitely ready," said the reigning Australian Open champion, who was suffering from a shoulder problem before damaging an ankle while dancing at a cousin's wedding.
"I'm happy that I gave myself an opportunity. It's better to try than not to try. If I had said: 'It's better not to come', that would be the attitude of a real loser."
Clijsters, also the defending US Open champion, had not appeared at Roland Garros since her semi-final defeat by Justine Henin in 2006 and she will not reflect too happily on the two matches she has played this week in Paris.
Given her lack of competitive preparation, a lack of sharpness was perhaps inevitable but such a collapse after leading 3-0 and 5-2 in the second set will not sit comfortably with the four-time Grand Slam winner.
It was her worst performance at Roland Garros since she lost in the first round in 2000 and the last time she did not reach round three in a Grand Slam was at Wimbledon in 2002.
Clijsters, who committed 65 unforced errors, raced 3-0 ahead in sets one and two but was pegged back on both occasions.
Rus, 22, twice broke serve when Clijsters was standing on the verge of victory - and worse was to follow for the 2001 and 2003 finalist.
Game one of the third set went the way of Clijsters but her performance became error-strewn and Rus broke to lead 2-1 before going on to secure a famous win.
"I just wanted to go for every point. I'd like to play every day like this," said Rus, who had only previously won one match this year.
"It was my biggest win. She is my hero. I played fantastic tennis. I was a little nervous as it was my first time on the stadium. When I faced match points, I thought 'just go for it'. I was more aggressive in the second set."
Regarding her physical state, Clijsters added: "The ankle is fine. It had nothing to do with it. I am still trying to find out what happened. I felt in control, she was missing a lot in the rallies and I was moving well.
"Then I started doubting myself and that's the wrong attitude to have on clay. She built up more confidence and put me on the back foot."
Next up for Rus is 25th seed Kirilenko after the Russian beat Chanelle Scheepers 6-1 6-4.
It looked as if another huge upset could be on the cards when Sharapova found herself in deep trouble against 17-year-old world number 188 Garcia.
The former world number one and three-time Grand Slam champion looked down and out but managed to pick up 11 successive games to avoid humiliation.
Sharapova will take on Taiwan's Chan Yung-Jan for a place in the last 16.
"She played unbelievable and the conditions were really tough," said Sharapova on a windswept Court Philippe Chatrier. "So I tried to be steady and to adjust the best I could.
"In the first set-and-a-half there wasn't much I could do, she's young and was tough from the beginning. I was just trying to stay in it. I had to adjust and turned things around."
Garcia was playing in only her second tour level event, having made the second round at the Australian Open on her debut in January.
But she looked to be full of confidence from the outset and had a heavy-footed Sharapova chasing shadows for long periods.
Garcia enjoyed three breaks of serve en route to picking up the first set and when Sharapova put a forehand long in game five of the second she stood two games from victory.
However, Sharapova powered her way to 4-4 and a crucial over-rule at 30-30 in the next game swung the tie firmly in the Russian's favour.
She levelled the match and then stormed through the deciding set.
Despite her defeat, Garcia's display left experienced observers impressed and world number four Andy Murray used social networking site Twitter to say: "[She] is going to be number one in the world one day, what a player u heard it here first."
Elsewhere, sixth seed Li Na advanced with a 6-4 7-5 victory over Silvia Soler-Espinosa and ninth seed Petra Kvitova brushed aside Zheng Jie 6-4 6-1.
Agnieszka Radwanska, seeded 12th, was similarly untroubled against Sania Mirza and 15th seed Andrea Petkovic overcame Lucie Hradecka 7-6 (7-2) 6-2.
The other seeds to progress were Yanina Wickmayer, Alexandra Dulgheru and Roberta Vinci.