American Russell Henley emerged as the last man standing to win his second PGA Tour title in a four-way playoff for the Honda Classic at Palm Beach Gardens in Florida.
Henley, 24, birdied the first extra hole, the par-five 18th, from two feet in fading light to edge out Northern Irishman Rory McIlroy, American Ryan Palmer and Scotland's Russell Knox on a dramatic afternoon at PGA National.
McIlroy surrendered a big lead with an error-strewn 74 in the final round, though he made a birdie at the 72nd hole to qualify for the playoff after hitting a superb second shot to 11 feet, only to miss the eagle putt.
Henley (72), Palmer (69) and Knox (71) also made mistakes over the closing stretch to finish level with McIlroy at eight-under-par 272.
Henley sounded as if was still in shock as he spoke of his victory.
"I hope I can have a bunch more Sundays just like that in my career," he told Golf Channel. "It was a rush to be out there playing with Rory and the crowd.
"I've never been part of a crowd so big cheering for me. It was an amazing feeling. It was so much fun."
McIlroy fades again
Henley appeared to have thrown away a chance of winning when he dunked his six-iron into the water at the par-three 15th for a double-bogey.
But he steadied his apparently sinking ship with pars on the final three holes, which was enough to make the playoff.
"I was so nervous coming down the stretch," said Henley, who won his maiden PGA Tour title at last year's Sony Open in Hawaii. "Just hanging in there and trying to enjoy every step."
Four weeks ago, McIlroy had a similar if less dramatic fade during the final round of the European Tour's Dubai Desert Classic.
He started the final day just two strokes off the lead but slipped back with a closing 74 to finish joint ninth.
World number one Tiger Woods was forced to withdraw during the final round, citing a back injury.
Woods retired on the 13th hole at PGA National, where he was five over par for the day and level for the tournament, having struggled to the turn in five-over 40.