Former winner Maria Sharapova, her Russian compatriot Anna Chakvetadze and Serb Ana Ivanovic joined world number one Justine Henin in the semi-finals of the WTA Championships on Thursday.
Sharapova booked her place after fighting her way back from a set down to overpower world number two Svetlana Kuznetsova 5-7, 6-2, 6-2, while Chakvetadze recovered from a second-set wobble to beat world number three Jelena Jankovic 6-4, 0-6, 6-3.
Ivanovic made the last four thanks to Sharapova's victory, with the two players meeting on Friday to decide who will advance as group winner and avoid Henin in the semi-finals.
Henin had already booked her place from the yellow group but there was no letting up from the Belgian in her final round-robin match as she demolished Marion Bartoli 6-0, 6-0 in 57 minutes.
Bartoli, who stepped into the event after Serena Williams withdrew because of a knee injury during her opening match on Wednesday, beat Henin in the semi-finals of Wimbledon this year.
But she was never given a chance to settle as the 2006 champion blew her away with some sublime tennis to inflict the heaviest defeat in the 35-year history of the season-ending Championships.
"It was a great one, almost everything was perfect tonight," said Henin. "I showed lots of determination and wanted to get my revenge."
Sharapova, who won the prestigious event in 2004 but whose season has been disrupted by injury, recovered from a slow start to produce some top-class tennis against Kuznetsova.
She found her rhythm in the second set and started stretching Kuznetsova around the court with some heavy ground strokes to record breaks in the fifth and seventh games.
In the third set, a Kuznetsova double fault gifted Sharapova three break points in the fifth game which she took at the first opportunity with a brilliant backhand cross-court winner and she broke again in the seventh on her way to a confident victory.
"She hurt me in the first set but I got hold of myself and stayed tough and positive which was really good," said Sharapova.
Chakvetadze edged the first set against Jankovic, but looked to be wilting after losing the second 6-0 and surrendering her serve in the opening game of the decider.
But the Russian recovered to rattle off the next four games to go 4-1 up and then held her nerve to clinch the victory.
"It was a very tough match, a very nervous match with a lot of ups and downs, said Chakvetadze. "I'm so tired right now I just want to go to sleep."