Czech Lucie Safarova stunned world number five Svetlana Kuznetsova of Russia 6-3, 6-4 to set up a semi-final clash with Belgium's Justine Henin at the Paris Open on Friday.
Saturday's other semi-final will feature holder Amelie Mauresmo of France against Russian fourth seed Nadia Petrova.
Former world number one Henin, returning to competitive tennis after a three-month break for personal reasons, outlasted Frenchwoman Tatiana Golovin 6-2, 3-6, 6-3.
Top seed Henin, whose last competitive match was winning the season-ending Tour championships in Madrid on Nov 12, started brightly.
She played very aggressive tennis to break twice and seemed on track for an easy win after wrapping up the first set in 30 minutes.
The 19-year-old Golovin fought back, however, making the best of her sole break opportunity in the second set to take a 4-2 lead and level the tie with a fine crosscourt forehand.
Henin then found her way to the net and, despite Golovin saving three break points, the Belgian sealed the victory in one hour and 57 minutes on her first match point.
CONFIDENT HENIN
"It is the way I have to play. When I stay on the baseline, it does not work," Henin said.
"I took my responsibilities and I am proud of that. I now have to be more consistent but winning two matches for my return is good for my confidence."
On Friday she will face Safarova, who upset Kuznetsova in style.
"She is on the rise, she is a very impressive player who will have nothing to lose," Henin added.
Safarova, who broke into the limelight last month when she beat champion Mauresmo to reach the Australian Open quarter-finals, won in one hour and 21 minutes.
The 20-year-old Czech, who is 32nd in the world rankings, got off to a flying start, breaking in the first game on Kuznetsova's fourth double fault.
Safarova dictated the points, forcing her opponent behind her baseline and claiming the first set in 39 minutes after breaking a second time.
STUNNING FOREHAND
Both players held serve until the 10th game of the second set when unseeded Safarova broke again to snatch an impressive win with a stunning forehand.
"I'm so happy to win this match, it was so hard. It's just amazing for me," said Safarova.
Earlier on Friday, Nadia Petrova booked her place in the last four with a clinical 6-3, 6-2 victory over Dinara Safina in an all-Russian clash.
She now meets local darling Mauresmo, who fought to a 7-6, 7-5 victory over eighth seed Anna Chakvetadze.
The Russian world number 13, who won the Hobart tournament last month, saved two set points on her serve before breaking back to stay in contention and force Mauresmo into a tiebreak the Wimbledon champion won 7-5 after 67 minutes.
Both players held serve until the 11th game of the second set when Mauresmo decisively broke her opponent to serve for the match as Chakvetadze burst into tears.
Mauresmo wrapped up the victory on her fourth match point after battling for just over two hours when Chakvetadze sent a backhand wide.
"She does not let anuthing go. I wish I had pushed harder when I was leading 5-2 in the first set," said Mauresmo.
"It has been a great test, physically and mentally."
World number seven Petrova played solid tennis throughout to beat Safina, a Paris winner in 2005, in just over an hour.
"First set we were both very tense, you could feel the tension on the court," said Petrova.
"I was very strong mentally and then started to play better and better. Now I'm looking to the next level."
