Jo-Wilfried Tsonga will play Roger Federer in the final of the ATP World Tour Finals after beating Tomas Berdych in straight sets at London's O2 Arena.
The Frenchman dominated the first set before riding out a nervy second to win 6-3 7-5 in an hour and 33 minutes.
Berdych came from a set and a break down to beat David Ferrer on Friday and it seemed history might repeat itself.
But the Czech was punished for an error-strewn display as the big-hitting crowd favourite sealed victory.
Both men were contesting their first season-end championship semi-final and seeking to reach the second-biggest final of their careers.
Tsonga was runner-up at the 2008 Australian Open while Berdych made it to the Wimbledon showpiece in 2010, but that is where the similarities ended on this occasion.
Comfortable service holds were exchanged at the start of the match before Berdych got a look-in on his opponent's delivery in game five.
A winning backhand return gave the Czech 15-30 but four straight errors saw the chance squandered, and that profligacy would prove costly.
He opened game six with another mistake, followed it up with a double-fault and then netted a forehand to fall 15-40 down. Berdych fired long on the second break point.
Tsonga breezed through his next two service games to wrap up the first set and pushed hard again at the start of the second, engineering two break points.
Both were saved but the pressure mounted in game seven and this time Berdych cracked, a double fault gifting Tsonga a 4-3 lead.
For the first time all night Tsonga looked nervous and a double-fault helped Berdych to 15-40 before the Frenchman netted a forehand to level things up.
However, Berdych's groundstrokes deserted him when it mattered most. Tsonga pounced for 6-5 and then sealed his place in Sunday's final with a thunderous ace out wide.
Eighth-seeded Poles Mariusz Fyrstenberg and Marcin Matkowski will meet third seeds Daniel Nestor and Max Mirnyi in Sunday's doubles final.
Fyrstenberg and Matkowski beat fourth seeds and three-time finalists Mahesh Bhupathi and Leander Paes 6-4 4-6 10-6 in one hour and 39 minutes to reach their 31st Tour-level doubles final.
Nestor and Mirnyi won 33 of their first 35 service points to beat top seeds and three-time champions Bob Bryan and Mike Bryan 7-6 (8-6) 6-4.