Elena Dementieva gave herself a birthday present on Friday by crushing her arch-rival Svetlana Kuznetsova 6-1, 6-3 in a rematch of last month's all-Russian U.S. Open final to reach the Kremlin Cup semi-finals.
Earlier, second seed and the new world number one Lindsay Davenport reached her 13th semi-final of the year with a 6-4, 6-1 victory over unseeded Italian Francesca Schiavone.
But former world number one Venus Williams was unceremoniously dumped out of the $2.3 million Moscow tournament by unseeded Russian Elena Bovina 6-3, 6-2.
Williams, visibly shaken, said: "No loss is a lot of fun. My serve wasn't there the way I wanted to be."
The seventh seed served 10 double faults and completed only 51 percent of her first serves.
On the men's side, unseeded Briton Greg Rusedski upset second seed Joachim Johansson of Sweden in three tough tie-break sets which lasted more than 150 minutes.
Dementieva meets Bovina in Saturday's semi-finals while Davenport will face French Open champion Anastasia Myskina, who edged her Russian Fed Cup team mate and close friend Vera Zvonareva 4-6, 6-0, 7-5.
Jubilant Dementieva threw her racket and pumped both fists into the air at the end of her 69-minute match with Kuznetsova.
"It was very important for me to win this match, to beat her this time," the fifth seed said.
It was the first meeting between the pair since their memorable final at Flushing Meadow where Kuznetsova won her maiden Grand
Kuznetsova, who admitted the two are not the best of friends, said: "I don't think she won the match, it was me who lost it."
UNFORCED ERRORS
"I played so badly that I wasn't even in this match, just look at the number of my mistakes," added the fourth seed, who committed 47 unforced errors.
"At the end she was celebrating as if she just won a grand slam. It just shows how desperate she was for a win."
In a battle between two power hitters in the men's tournament, Johansson fired more aces than Rusedski, 33 to 32.
But the Canadian-born Briton was the one who advanced to the last four where he will meet third-seeded Slovak Dominik Hrbaty, who prevailed over unseeded Russian Igor Kunitsyn 7-6, 6-4.
"I was very pleased how I played, how we both played," said Rusedski, who is trying to get his tennis career on track after battling injury and being cleared of doping charges.
"I dominated the first two sets, especially the first set. The second set I had more break chances, but he played a great tiebreaker. Fortunately, I started serving better in the third set."
The second semi-final will be an all-Russian affair between fifth-seeded Mikhail Youzhny and eighth seed Nikolay Davydenko.
Russia's 2002 Davis Cup hero Youzhny beat unseeded Dane Kenneth Carlsen 6-2, 7-6. Davydenko overcame Radek Stepanek 7-6, 5-7, 6-1. The Czech had knocked out top seed Marat Safin in the previous round.