England’s Danny Willett fired a five-under-par final round to claim a stunning US Masters win, as defending champion Jordan Spieth faltered badly on the back nine.
Willett shot a final-round 67 to end on five-under for the tournament – three shots ahead of Spieth and Englishman Lee Westwood.
The victory is 28-year-old Willett’s maiden major, and it came about in dramatic fashion in an action-packed last day at Augusta.
Overnight leader Spieth had a five-shot lead going into the 10th, but the following three holes brought about a huge swing in momentum.
The 22-year-old Texan bogeyed the 10th and 11th, before scoring a quadruple-bogey on the 12th.
That meltdown handed world number 12 Willett the lead.
The Englishman, playing three groups ahead of Spieth, ended with a superb final-round 67, taking him to five-under-par for the tournament, and his victory was sealed when Spieth bogeyed the 17th.
It was a remarkable turnaround in fortunes, and gave Willett the first Masters win for an Englishman in 20 years, and the first for a European since Jose Maria Olazabel in 1999.
Fellow Englishman Lee Westwood ended with a three-under-par 69, to finish joint-second with Spieth. Westwood was within one shot of the lead after eagling the 15th but bogeyed the next hole and finished with two pars to fall short of Willett.
Willett’s win caps a dramatic rise for the Englishman, whose participation at Augusta was in doubt before the tournament as his wife Nicola was due to give birth on the final day. However, their son Zachariah arrived early, meaning Willett was free to compete.
His solid opening three rounds of 70, 74 and 72 had put him within touch of Spieth going into the last day.
A superb final round which included five birdies and no dropped shots sealed victory for Willett in just his second appearance at Augusta.
After the win, Willett said: "It's been crazy. You can't really describe the emotions and feelings.
"We all try to play good golf and someone has to win and fortunately today it was my day.
"It was a very surreal day when you look back at the ebbs and flows."
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Willett’s brilliant final day performance should be lauded, but his victory owed much to the usually unshakeable Spieth’s back-nine implosion.
Spieth looked well-set to become just the fourth man in history to win back-to-back Masters, but a catastrophic par-three 12th hole put paid to his hopes.
After firing his tee shot into Rae's Creek, he lobbed a heavy second shot into the water, before finding the bunker at the back of the green.
Spieth managed to get onto the green and putt in for a quadruple bogey, and although he birdied the 15th to move to within two shots of the lead, the bogey at the 17th meant he couldn’t catch Willett.
Trying to explain the astonishing turnaround in fortunes, Spieth said: "It was just a lack of discipline coming off the two bogeys instead of realising I was still leading the Masters by a couple of shots."
"I have no doubt about my ability to close majors, I just think it was a very tough 30 minutes that hopefully I don't experience again."
Elsewhere, world number three Rory McIlroy, bidding to win the only Major that has so far eluded him, carded a final round 71, to leave him at one-over for the tournament.
World number one Jason Day also finished at one-over, after a final round of 73.
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A memorable final day’s play at Augusta also featured three holes-in-one at the par-three 16th – from Irishman Shane Lowry, American Davis Love, and a crazy ace from South African Louis Oosthuizen.