Chris Gotterup dug deep and, in his own words, "hung in there like a champ" to clinch the Scottish Open title on Sunday.
Gotterup sealed the biggest title of his career after impressively holding off Rory McIlroy to register a final round score of 66 to win by two shots at the Renaissance Club.
As well as winning his second PGA Tour title, the American also secured a debut appearance at The Open at Royal Portrush next week.
Gotterup was tied with McIlroy for the lead at 11-under heading into the final round, with a bogey on the first hole threatening to derail the world number 158's hopes of victory.
However, he responded emphatically, producing birdies on the third, seventh and eighth holes. But McIlroy kept pace, with the pair edging two shots clear of the field.
But the Northern Irishman's challenge for a second title faltered on the back nine, with the Masters champion producing 10-straight pars to close out his round.
A bogey at 15 put Gotterup under pressure again, but he remained composed and registered a birdie on the following hole to all but seal a stunning victory.
"I just hung in there tight and tried to keep it together. I knew it was going to be a grind and [Saturday] was a grind, too," Gotterup said.
"Hitting it in the bunker on the first hole, I'm like, uh-oh, here we go. But I held it together really well, and then it was so much fun out there.
"This is awesome. I'm not going to be able to keep it together. Amazing. It's all hitting me. It's just so cool. I played really well this week, and I knew today was going to be tough.
"I hung in there like a champ and finished it off in style."
McIlroy finished tied for second with Marco Penge, who, along with Matt Fitzpatrick, briefly held shares of the lead but were unable to keep up with Gotterup.
Justin Rose carded the round of the day, his seven-under 63 taking him to 11-under and a sixth-placed finish.
Nicolai Hojgaard, along with Gotterup, earned one of the final spots for The Open with a closing 64 that secured him a share of fourth, alongside Fitzpatrick, at 12-under.
Rounding off the top 10, Sepp Straka finished seventh on 10-under, while his Ryder Cup team-mate from Rome two years ago, Ludvig Aberg, carded a mixed final round of 68.
McIlroy believed he was "close to being back" to the level that saw him clinch his long-awaited Masters win, and was happy with his efforts ahead of The Open next week.
"It was pretty windy, and it was hard to get the ball super close," he said. "I gave myself plenty of chances coming down the stretch.
"The greens deteriorated as the week went on and just got a little bumpy.
"I had some putts that felt good but just didn't go in, whether they were misreads or poor speed here and there.
"But Chris played a great round of golf. He was so solid. After he got a couple ahead, I just couldn't claw back."
McIlroy also took the time to applaud Gotterup for his sensational achievement.
"I'm really happy with where my game is; the way I played over the weekend; the shots that I hit, how I controlled my ball flight," he said.
"It has been a great week. Missing the trophy, that's about it.
"There's no frustration, really. I'm really happy with where everything is. I feel like I've gotten out of this week everything, really, that I wanted."
