Washington - Matthew Wolff, a 20-year-old American in only his fourth US PGA event, sank a 26-foot eagle putt on the last hole on Sunday for a dramatic 3M Open victory.

Reigning US college champion Wolff became the second-youngest US PGA winner in 80 years by firing a six-under par 65 in the final round to edge compatriots Bryson DeChambeau and Colin Morikawa by a stroke.

"I just proved to myself I can be out here," Wolff said. "I knew I can (win). This week I just believed in myself. It's still settling in."

Wolff finished 72 holes on 21-under 263 at TPC Twin Cities in Blaine, Minnesota, to earn a PGA spot through the 2020-21 campaign and a berth in the 2020 Masters.

DeChambeau sank a six-foot eagle putt at the par-5 18th to seize the lead at 20-under with only Morikawa and Wolff, each one shot back, remaining.

The former Southern California high school rivals, each playing on a sponsor exemption, gave themselves long eagle putt opportunities.

Wolff, just shy of the green, rolled in his tension-packed putt to reclaim the lead and leave Morikawa, a former world amateur number one, a 22-foot eagle putt to force a playoff.

Morikawa's putt rolled just past the left side of the cup to give Wolff the victory, although he tapped in to share second.

Canada's Adam Hadwin was fourth on 266 with Mexico's Carlos Ortiz and American Wyndham Clark sharing fifth on 267.

American Lucas Glover, the 2009 US Open winner, equalled the course record with a 62, matching the low round of his career and shared seventh on 268.

The only player younger than Wolff to win a PGA event since 1939 was Jordan Spieth, who captured the 2013 John Deere Classic at age 19.

Only four players in PGA history have won with fewer starts than Wolff, who attended Oklahoma State.

Wolff shared 50th at the Phoenix Open in February as an amateur, 80th at last month Travelers Championship in his PGA pro debut and missed the cut last week in Detroit.

DeChambeau, 25, was denied a sixth career US PGA title and second win of the year after the European Tour's Dubai Desert Classic in January.

Morikawa, 22, was making only his sixth US PGA start and made a run of five birdies in six holes late to stay in the hunt to the end.

A back-nine last-day shootout was assured when the last group made the turn and 12 players were within two shots of the lead.

Ortiz grabbed the clubhouse lead with Hadwin, Clark and Wolff level on 17-under.

DeChambeau sank a three-foot birdie putt at 13 to join the co-leaders.

Morikawa, in the last duo, made it a six-way logjam at the top with his third consecutive birdie, rolling in a 10-footer at 13 to reach 17-under.

Wolff made a nine-foot birdie putt at the 14th to grab the lead and put his approach three feet from the cup at 15, setting up a birdie to reach 19-under.

But Morikawa, who put his approach inches from the hole, tapped in to stay one back of his playing partner.

DeChambeau sank a 16-foot birdie putt at 16 to reach 18-under but Morikawa made his fifth birdie in six holes on a 13-foot putt at 16 to match Wolff at 19-under.

Hadwin took the clubhouse lead by closing with a three-foot birdie putt as the tension built.

Morikawa lipped out on a 27-foot birdie putt at the par-3 17th and Wolff was just short from 23 feet to set up the last-hole thriller.

Leading scores after Sunday's final round of the US PGA Tour 3M Open at Blaine, Minnesota (USA unless noted, par-71):

263 - Matthew Wolff 69-67-62-65

264 - Bryson DeChambeau 66-62-70-66, Colin Morikawa 68-66-64-66

266 - Adam Hadwin (CAN) 64-66-69-67

267 - Carlos Ortiz (MEX) 67-67-69-64, Wyndham Clark 66-69-64-68

268 - Lucas Glover 67-72-67-62, Sam Burns 66-66-72-64, Brian Harman 65-67-71-65, Joey Garber 73-65-65-65, Troy Merritt 70-64-66-68, Hideki Matsuyama (JPN) 64-70-66-68

269 - Viktor Hovland (NOR) 69-66-69-65, Fabian Gomez (ARG) 68-68-68-65

270 - Charlie Danielson 73-66-64-67, Adam Svensson (CAN) 70-64-69-67, Shawn Stefani 69-66-68-67, Daniel Berger 68-66-69-67, Im Sung-jae (KOR) 65-70-68-67, Scott Brown 68-65-68-69, Scott Piercy 62-70-69-69, Roger Sloan (CAN) 67-67-67-69

271 - Brice Garnett 67-71-67-66, Denny McCarthy 66-68-70-67, Sam Saunders 65-67-72-67, Tom Hoge 68-71-65-67, Chase Wright 69-66-69-67, Patrick Reed 69-67-68-67, Tony Finau 66-68-69-68, Johnson Wagner 69-69-64-69, Arjun Atwal (IND) 65-68-68-70, Joaquin Niemann (CHI) 73-63-65-70, Charles Howell 68-66-66-71