Daniela Hantuchova dug deep to secure a first win over Venus Williams in 11 attempts and reach the semi-finals of the Aegon International at Eastbourne.
Slovakian Hantuchova, runner-up at last week's Aegon Classic in Birmingham, got off to a flying start with a double break in a one-sided first set.
American Williams began to show flashes of her best form as the wind played havoc in the second set.
But Hantuchova hit back with impressive calm to come through 6-2 5-7 6-2.
"I felt I came out and played well early in the match," said Hantuchova, ranked 29 in the world.
"But then the wind picked up and it got difficult for both of us. It was then about who had the mentality and I came through.
"This is my most favourite time of the year - the grass season - and I'm feeling really good. My form is good."
Hantuchova had to win the hard way, dropping a 4-2 lead in the second set to allow Williams to level at one set all, then being broken at 2-1 up in the third before striding away to secure the victory.
The Slovakian will now face Czech fifth seed Petra Kvitova in the last four after she recovered from a set down to beat Agnieszka Radwanska.
The Pole raced out of the blocks and looked to be cruising until Kvitova hit back and then edged through a third-set tie-breaker to win their quarter-final 1-6 6-2 7-6 (7-2).
In the other half of the draw, Australian Samantha Stosur fought back from a set down to dispatch Russian top seed Vera Zvonareva in a titanic two-hour-48-minute match.
The turning point appeared to be game 11 in the second set, when Stosur held her serve following 11 deuces, the seventh seed going on to seal a 4-6 7-6 (7-4) 6-4 win.
"It was a very tough match," she said. "The conditions were tough and I thought we both played pretty well considering."
Stosur goes on to face Frenchwoman Marion Bartoli in the semi-finals after her Belarusian opponent Victoria Azarenka was forced to retire at 2-6 0-2 down.
"Marion's a very tough player," said Stosur of her last-four opponent. "She's been playing very well lately and grass is probably her best surface. But I'll give it my best shot."
In the men's quarter-finals Italian Andreas Seppi was the first player to reach the last four after a 6-2 6-7 (5-7) 6-3 win over Belgian Olivier Rochus, who had already been on court earlier in the day to finish his second-round match against Carlos Berlocq.
Igor Kunitsyn of Russia will be Seppi's opponent in the final four after he easily ousted Frenchman Julien Benneteau 6-3 6-2.
Serbia's Janko Tipsarevic, like Rochus, had to see off Mikhail Kukushkin before beating Bulgarian Grigor Dimitrov 6-3 7-6 (7-2) to move within one match of the final.
He will face Kei Nishikori, another player whose second-round match crossed over to Thursday. The Japanese player beat qualifier Rainer Schuettler before surprising Radek Stepanek, who had beaten first seed Jo-Wilfred Tsonga in the previous round, with a 6-2 6-3 victory.