Caroline Wozniacki was dumped out of the French Open in the second round as Germany's Julia Goerges defeated the fifth seed 6-4 7-6 (7/4).
Wozniacki, who has failed to reach round three at Roland Garros since 2012, was overpowered by a superb Goerges performance.
Goerges, ranked 72nd in the world, has won all three meetings between the pair on clay and Wozniacki admits she has a mental block when she faces the German.
"I think, especially on clay, she has a way to make me feel like I'm not playing very well," the Dane said.
"I think there are just some players that it's a tough match-up for you no matter the rankings, and some of them are easy match-ups no matter the rankings.
"Obviously she has given me trouble in the past and she gave me trouble again today so that kind of sucks.
"I would have liked to have been through to the next round, but I'm not."
Goerges, who will now play American Irina Falconi, has never gone further than the fourth round at a major but she believes her style of play is difficult to combat on clay.
"I don't play the typical women's game on clay court," Goerges said.
"I play a little bit more spin, a little bit higher over the net than some of the other girls.
"When she gets the ball in her striking zone she doesn't miss any balls, but if you give her different balls then it's tougher for her.
"It's never a guarantee you're going to win the match, you have to execute as well, and that's what I did mainly today very well."
Also through to the third round is Italian Francesca Schiavone, who emerged victorious after another marathon contest with Russian 18th seed Svetlana Kuznetsova.
The pair played the longest ever women's grand slam match in the last 16 of the Australian Open four years ago, which Schiavone also won, and she had to dig deep again to claim a 6-7 (11/13) 7-5 10-8 victory.
The match lasted three hours and 50 minutes, short of their record four hours 44 minutes in 2011, while the final set lasted 94 minutes and included nine consecutive breaks of serve.
"She played unbelievable points," Kuznetsova said.
"There's nothing I can do, there are many other opportunities I have to think about on my serve. I was not too sharp enough today."
She added: "The time is for journalists to think about - the hours and minutes and whatever it is.
"I just think about the game. I was trying to hold my serve and I couldn't so it was a little bit frustrating for me.
"I can serve well, but I was getting tight and I was not serving the way I should."
World number one Serena Williams laboured to an unconvincing 5-7 6-3 6-3 win against Germany’s Anna-Lena Friedsam on Court Suzanne Lenglen.
It looked like a mismatch but 105th-ranked Friedsam gave the 19-time grand slam champion a torrid time, taking the first set off the American before a nervy Williams recovered to scrape into the third round 5-7 6-3 6-3.
The top seed saw her powerful groundstrokes regularly sailing over the baseline and even her fearsome serve deserted her in the first set - she was broken three times - as a noteworthy blot on her incredible grand slam record looked possible.
Even when she led 4-2 in the second set Williams looked shaky, trailing 0-40 and dropping serve, but once she got level and broke Friedsam's serve at the start of the decider she finally began to relax.
She will have to sharpen up considerably though against former world number one Victoria Azarenka in the next round.
The tournament is over, however, for Britain's Heather Watson after she lost 6-2 6-4 to America's Sloane Stephens.
