Top seed Justine Henin staged a spectacular recovery to knock out Swiss Patty Schnyder 3-6, 6-4, 7-5 on Thursday and reach the Qatar Open semi-finals.
The Belgian next meets fourth-seeded Serb Jelena Jankovic, a 6-3, 6-3 winner over Ukraine's Katerina Bondarenko.
Slovak Daniela Hantuchova came back from the brink to oust Martina Hingis 1-6, 6-4, 6-4 and set up a clash with second seed Svetlana Kuznetsova of Russia, who defeated Italy's Francesca Schiavone 6-3, 6-4.
Fifth seed Schnyder adapted better to the slow court as she took the first set against Henin.
The world number two clawed her way back to snatch the second before facing a match point in the third, at 4-5 and 30-40 down.
A lucky net cord, though, helped Henin get back to 5-5 and she broke serve in the 12th game to seal victory.
TOUGH MATCH
"It was a tough match but I had predicted it," Henin told reporters. "Patty is a good player and we have had some tough matches in the past.
"We are always involved in big fights, in three sets. She is a special player as she is a left-hander."
Third seed Hingis appeared to be coasting to victory as she led by a set and 4-1.
But Hantuchova, seeded six, then began to find her range from the baseline and put the Swiss under pressure for the first time.
She broke Hingis in the seventh and ninth games, wrapping up the set with a cross-court forehand.
Hantuchova raced into a 4-2 lead in the decider only for Hingis to level at 4-4.
Having restored parity, the former world number one then dropped her serve again.
"I never felt I was out of it," said Hantuchova. "Even though she was 4-1 up in the second set, I slowly started to believe I was doing the right thing.
"I thought it was just a matter of time to break her down. But I really liked the way I turned the match around and found a way to get through."