Warwickshire's Paul Broadhurst kept a cool head to retain his grip on the Portuguese Open trophy with a birdie at the 72nd hole.
The 40-year-old from Atherstone finished with a 17-under-par total of 271, one shot clear of fellow Englishman Anthony Wall.
Broadhurst posted a 67 on the final day, despite finding trouble on the back nine.
He came to the final hole level with Wall after a bogey at the 17th, then pushed his second shot at the last into the rough at the side of the green.
But he played a superb pitch and rolled in a three-foot putt for a nerve-jangling victory.
Broadhurst said: "When I was standing on the 18th tee, I thought to myself that I would never have a better chance of winning a tournament.
"I got a decent lie for my approach and was confident of getting it to within six feet. I thought it had gone in. This was a big test for me today and I felt a bit under the cosh."
Wall had a third successive 67, with Andres Romero, of Argentina, finishing third on 15-under.
Broadhurst stormed to the turn in 30 with five birdies to become the clear favourite.
He then chipped in from the side of the green at the 12th to go to 17-under for the tournament.
Broadhurst found the water at the short 13th and chalked up a double bogey. but he recovered at the next where he picked up a shot before digging in for victory.
Broadhurst said: "All day I was thinking to myself, just play, and don't be concerned about leading the field. The wind was doing all sort of tricks but I didn't really hit a bad shot until 13."
Wall was already preparing for a play-off when Broad-hurst birdied the last. But the 30-year-old's performance was all the more remarkable given that he had not eaten since Friday because of a stomach bug.
An eagle at the fifth and a birdie at the next saw Wall gain some momentum. He then kept his nerve when the heat was on with birdies at three of the last four holes.
It was not to be for Wall but finishing runner-up will do wonders for his confidence.
Wall, ranked 97th on the European Tour, said: "I am thrilled because this is the biggest cheque of my career. I was pleased with the way I finished as I played a lot of good shots."
Ryder Cup captain Ian Woosnam also rediscovered his touch in the Algarve ahead of the US Masters which starts on Thursday at Augusta. He finished with a 69 and a total of 282, six-under for the tournament.
Warwickshire's Tom Whitehouse also had reason to be satisfied with his week. After opening with two level-par rounds on Thursday and Friday, consecutive scores of 68 over the weekend left the Maxstoke Park man on eight-under and in joint-12th position.
Wolverhampton's Peter Baker also improved from halfway, going from level-par on Friday night to five-under, thanks to Saturday's round of 71 and a best-of-the-week 68 yesterday.
Warwickshire's Steve Webster was alongside Baker and three rounds of 70 and Friday's 73, but Worcestershire's John Bickerton kept his worst for last, yesterday's round of 74 pushing him back to level par after Saturday's 71.