Michael Hoey captured his maiden European Tour title when he beat Spain's Gonzalo Fernandez-Castaño at the third extra hole in the Estoril Open de Portugal.
The Ulsterman feared he has blown his title chances when he missed an eight footer for a birdie at the 18th.
But his 66 was good enough to force a play-off on seven under par and he then got up and down three times in extra time, holing from eight feet at the 17th to win €208,330.
He said: "It's a joke really - a bit of a dream.
"I didn't really think about winning going out, but I was lucky - I got all the breaks.
"I couldn't believe I was in the play-off, let alone getting up and down, up and down, up and down."
The Belfast man fired a brilliant five under par 66 to finish level with the Spaniard, who carded a 68, on seven-under par
But it was Hoey who kept his nerve on the third play-off hole, knocking in an eight footer for par following Fernandez-Castaño's bogey at the 474-yard, par four 17th.
The play-off began with two trips down the 18th with both men getting up and down for par - Fernandez-Castano from eight feet and Hoey from four.
The Spaniard almost converted a 35-foot birdie attempt the second time around as Hoey, short of the green once more, sank a five-footer to stay alive.
When they switched to the 17th they missed the green again. This time, however, Fernandez-Castano missed from 12 feet and Hoey seized his chance.
Hoey was British amateur champion in 2001, played with Donald, McDowell and Dougherty in the victory in Georgia later the same year and the following year was just one shot away from becoming the first British amateur to make the cut in The Masters since Peter McEvoy in 1978.
But while they were instant hits in the pro ranks, he struggled even to get on Tour.
He did come through the Challenge circuit in 2005, but was back at the qualifying school for the sixth time last November.
Finally coming through that gave him confidence, as did a sixth-place finish in Madeira two weeks ago. But victory still came as a shock.