Russia's Anastasia Myskina sent Venus Williams tumbling out of the French Open in the quarter-finals.
Venus' loss came barely half an hour after her sister Serena's defeat to Jennifer Capriati over on Centre Court.
Venus, the fourth seed, committed far too many errors against Myskina, who reached the semi-finals of a Grand Slam for the first time with a 6-3 6-4 win.
Myskina, the sixth seed, will meet 2001 French Open champion Capriati in Thursday's semi-finals.
"It's a dream for me for sure," Myskina said.
"Venus is an unbelievable player and kept fighting so I knew I had to win this match and I am just so happy."
Williams was unable to play in the weeks leading up to the tournament because of an ankle injury, and she admitted it had been a factor.
"I would have liked better preparation," she said.
"I wasn't really in a rhythm today. Normally, I don't think she would beat me because she can't hurt me. Next time I will be ready.
"The opposition are getting stronger. They have lifted their level but if I am healthy I will be playing well."
Myskina had lost both her previous meetings to Williams but the 22-year-old was the quickest to settle in the cool, damp conditions on the Suzanne Lenglen court.
She raced into a 4-0 lead thanks to two breaks of serves and held onto her advantage to take the first set after 28 minutes when Venus hit a forehand long.
Williams hit 18 unforced errors to Myskina's eight in the opener as she struggled to make any impression against the faster Russian.
Myskina broke again in the first game of the second set but Williams held on valiantly to break straight back.
Crucially, the sixth seed gained a break to love to lead 4-3 and then held to go 5-3 before the fourth seed clung on at 5-4 down.
Williams carved out three break points but Myskina saved all three and then set up a match point with a fine running forehand.
She clinched the biggest win of her career after 72 minutes when the American
smashed another careless backhand from the baseline long.
It was Williams' 43rd unforced error of a the day.