Shane Lowry overturned a four-shot deficit at the start of the final day to win the Portugal Masters by one stroke ahead of Ross Fisher.
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Three years after capturing the Irish Open as an amateur, the Irishman produced a final round of 66 at the Oceanico Victoria golf course for a 14-under-par total of 270.
The 25-year-old's victory was set up by an eagle two at the 11th after his approach landed a foot short of the hole and hopped in.
After birdies at the 15th and 17th, Lowry got himself in a spot of bother after driving into sand and bogeying the last for a 66.
Fisher, though, failed to force a sudden-death play-off after also finishing with a bogey, coming home with a 70.
"I can't explain how I feel now to be honest. It's a dream," said Lowry, who is only the second player to win on the European Tour as an amateur and a professional after Spain's Pablo Martin.
"I've won such a big tournament, such a prestigious event. I'm over the moon. It was like playing in Ireland [given the fans' support], it was great."
Former US Open champion Michael Campbell was third, his highest finish in four years, with a 273 with overnight leader Austrian Bernd Wiesberger, another shot behind.
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