Rasmus Højgaard holed out twice as he pipped local favourite Rory McIlroy to win the Amgen Irish Open at Royal County Down.
McIlroy looked on course to claim his first professional win on home soil when he led by two shots with four holes to play at a venue just an hour from where he grew up.
However, while Højgaard completed a superb closing 65 with four birdies in the last five holes, McIlroy crucially bogeyed the 17th and then agonisingly missed an eagle putt on the 18th which would have forced a play-off.
The World Number Three had taken a one-shot lead into the final round and made the ideal start with birdies on the first and second.
With playing partner Matteo Manassero then dropping shots on the third and fourth, McIlroy briefly enjoyed a four-shot lead before making a bogey on the seventh after failing to get up and down from left of the green.
McIlroy then missed from inside 10 feet for birdie on both the eighth and the ninth as Højgaard kickstarted his challenge with an outrageous chip-in for birdie on the 10th.
A birdie on the 11th edged McIlroy two in front again, but that advantage was wiped out as Højgaard birdied the 16th and McIlroy bogeyed the 15th.
Højgaard then dramatically holed out from a greenside bunker on the 17th and, although McIlroy drew level with a birdie on the 16th, the four-time Major winner charged his birdie putt on the 17th past the hole and missed the return.
Højgaard’s third birdie in a row on the 18th meant McIlroy needed to make an eagle on the same hole to force a play-off and a towering approach from 191 yards gave him a chance from 15 feet, only for the eagle putt to slide just wide.
“It was a hard watch in the end but I had a number today that I was trying to reach, and that was eight (under),” Hojgaard said after securing his fifth DP World Tour title.
“Obviously coming in and finishing on nine was gold and I’m so happy. The game’s been trending for a while now and to get this one is massive.
“On 10 I got away with a good lie. Thought I hit a great chip there and maybe would have been five, six feet past, but then there was a flag in the way.
“And on 17 I was a bit worried I could be plugged in the bunker but coming up to an uphill lie in the bunker gave me a little bit more confidence that I could get it up and down. To hole it was key.”
Manassero finished third after a closing 69, with England's Daniel Brown fourth on six under after signing for a fine round of 66.