St Andrews -Lucas Bjerregaard's barnstorming final round at St Andrews on Sunday saw the Dane take advantage of a back-nine collapse from Tyrrell Hatton, who missed out on a third successive Alfred Dunhill Links Championship title.
England's Hatton held a five-stroke lead after a run of four consecutive front-nine birdies, but fell apart on the back nine with four bogeys.
Hatton, bidding to become just the second Englishman after Nick Faldo to win the same European Tour event three years in a row, started the final round with a one-stroke advantage, but missed a birdie putt at the last to force a play-off.
On a day when tee-off times were brought forward because of exceptionally strong winds, with a 'shotgun start' in which the field all commenced their rounds at the same time, Hatton failed to match Faldo's achievement at the 1991-1993 Irish Opens.
"Momentum completely went I think after the tee shot on 10. For some reason, just couldn't seem to do anything right," said Hatton.
"Tried my best but just you need some good breaks I guess when things aren't quite going your way.
"Unfortunately that didn't quite happen for me on the back nine and I guess my putt on the last to get in the playoff sums it up, really."
The 26-year-old was pipped by Bjerregaard's impressive five-under-par-67, which saw the Dane finish on 15-under for the tournament.
That left him a shot in front of Hatton and fellow English Ryder Cup-winner Tommy Fleetwood, who fired a 69 on Sunday.
World number 92 Bjerregaard had just one previous Tour victory to his name, at the 2017 Portugal Masters.
"It feels amazing. It's been a really good year. Just got a whole lot better now. It was tough out there today. The conditions weren't easy," said Bjerregaard.
Starting the day four shots adrift of Hatton, he quicky reduced the deficit with an opening birdie after starting on the 18th hole.
But the 26th-ranked Hatton looked to be cruising to victory on the Old Course as he raced to 18-under overall, only to combust on the home straight.
Bjerregaard still had an anxious wait in the clubhouse after a bogey on his final hole, the 17th, but Hatton missed his birdie try on the short par-four last.
Leading fourth-round scores and totals in the Alfred Dunhill Links
European Tour event at Carnoustie, Kingsbarns and St Andrews on Sunday
(par 72, GBR and IRL unless stated):
273 - Lucas Bjerregaard (DEN) 70-65-71-67
274 - Tommy Fleetwood 71-67-67-69, Tyrrell Hatton 70-66-66-72
276 - Tapio Pulkkanen (FIN) 76-67-64-69
278 - Li Haotong (CHN) 75-69-68-66, Andrea Pavan (ITA) 72-63-71-72
- Brooks Koepka (USA) 70-72-65-72, Tony Finau (USA) 73-66-71-69, Lucas
Herbert (AUS) 70-70-69-70, Padraig Harrington 69-72-69-69
Marcus Kinhult (SWE) 70-70-69-71, Nicolas Colsaerts (BEL) 72-70-67-71,
Matthias Schwab (AUT) 69-67-71-73, Peter Hanson (SWE) 70-71-70-69, Tom
Lewis 71-71-67-71, Andrew Sullivan 72-71-67-70, Stephen Gallacher
71-68-66 75, Nacho Elvira (ESP) 75-67-69-69, Marcus Fraser (AUS)