WASHINGTON (AFP) — Jackson Koivun, playing only his third PGA Tour event as a professional, held off top-ranked Scottie Scheffler in the final round on Sunday to capture the 3M Open in record fashion.

The 21-year-old American fired a five-under par 66 to finish 72 holes in a tournament record 25-under par 259 at TPC Twin Cities in Blaine, Minnesota, to defeat Scheffler by three strokes.

"I played a great round of golf," Koivun said.

"Had some nerves coming down 18. All throughout the crowd I kept hearing, 'Scottie's coming, Scottie's coming.’”

"I just tried to tune that out and keep playing the golf I knew I could and was able to find some good putts coming down the stretch."

American Lee Hodges set the prior 3M Open scoring record at 24-under 260 to win in 2023.

Former world amateur No. 1 Koivun, who didn't miss a putt inside five feet all week, fired a 61 on Saturday to lead by three on the way to his first PGA triumph in just 24 days as a pro, poised and calm under pressure.

Koivun took some of his aggressive shotmaking from words written on his glove — confidence, trust and dominate.

"Dominate is a word I came up with in college because I wanted to see how good I can play," Koivun said. "It helped me a lot in college golf with my mindset and I just kept doing it."

Scheffler, a four-time major winner, fired a bogey-free 63 to finish second on 262 with Brian Harman, the 2023 British Open champion, fellow Americans Denny McCarthy and Chandler Phillips and Japan's Hideki Matsuyama, the 2021 Masters winner, sharing third on 264.

Scheffler birdied six of his first 12 holes but the 30-year-old American came up short in what would have been the greatest last-round comeback of his career, having started six adrift.

"Not everything I hoped for," Scheffler said. "I did what I could today. I was close... put up a good fight. Played nice today."

Scheffler, who won in January in the California desert, now has five runner-up efforts, including the Masters, among 11 top-four finishes this year.

At the first, Koivun landed his approach inches from the hole and tapped in for birdie.

Scheffler birdied three of the first eight holes to join a second-place pack.

Koivun, however, sank an 11-foot birdie putt at the par-three fourth and a tap-in birdie at the par-five sixth to grab a five-shot edge.

Scheffler began the back nine with three birdies, holing a four-foot putt at 10, a 28-foot putt at 11 and another from just outside 12 feet at the par-five 12th to reach 20-under and pull within three of the lead.

Koivun answered with a par putt from just inside 15 feet at nine to keep that margin at the turn.

Koivun sank a 10-foot birdie putt at 12, but Scheffler, who lipped out a five-foot birdie putt at 14, responded with a birdie putt from just inside five feet at 16 to stay three adrift.

Scheffler birdied the par-five 18th from just inside five feet to reach the clubhouse two off the lead.

Koivun drove the green at the par-four 16th and birdied from just outside five feet to restore his three-stroke edge, then parred 17 and closed with a par putt at 18 from just inside 14 feet for the victory.