Finland's Mikko Ilonen defeated world number five Henrik Stenson 3&1 to win the World Match Play at the London Club in Kent.
Ilonen, the world number 52, carded four birdies in a bogey-free round to seal the biggest win of his career.
Stenson, three down after 12, birdied 13, only for Ilonen to hole a 12-footer to go three up with four to play.
The Swedish Ryder Cup player pulled one back but was unable to do any more as Ilonen sealed it on the 17th.
"The game plan was not to make any mistakes, you can't afford those with Henrik," said Ilonen, who takes his fifth win on the European Tour.
"I felt really comfortable going into the final. I felt like I had a good chance of beating him and I did."
Stenson won the FedEx Cup and the Race to Dubai last year but is still searching for his first tournament victory of 2014.
"I exceeded my expectations for the week," he said. "I didn't play my best, I was unlucky on a couple of putts but the best player won."
Stenson had earlier won his semi-final against South Africa's George Coetzee on the final hole, while Ilonen defeated Dutchman Joost Luiten 2&1.
Coetzee and Luiten could not be separated over 18 holes in the third-place play-off, with the latter taking it at the first extra hole.