Home hero Bradley Dredge suffered a final hole horror as Richard Sterne snatched the Celtic Manor Wales Open.
The Welsh favourite clawed back a four-shot deficit to lead by one with one to play at the Roman Road course.
But a bogey at the 18th left him one stroke adrift of South African Sterne who finished with a birdie to grab the £250,000 first prize.
Just two weeks after losing to Padraig Harrington in sudden death at the Irish Open, Dredge also looks certain to miss out on an automatic spot in next month's Open at Carnoustie as a top-50 player.
Dredge groaned: "I really feel this is a kick in the nuts."
There was also agony for Kilkenny's Gary Murphy as he birdied three of the last six holes but finished two behind the winner in a share of sixth place on 11 under after a 66.
Sterne, 25, who covered the back nine in five under par 29 for a closing 65, holing from five feet at the last for his second European Tour win.
Dredge needed a par at the last to force a play-off again but mistakenly thought he needed a par to win.
He said: "I thought I needed a par to win and I thought I had carried the bunker on the last.
"When I was walking up to my pitch my caddie told me I had to get up and down. I hit a good pitch, but missed the putt.
"Tension? There's always tension over a six-footer. There was a lot of tension over all the putts today."