Tony Finau charged late to card a four-under par 67 on Sunday to win his third US PGA Tour title at the 3M Open as fellow American Scott Piercy stumbled down the stretch.

Finau, ranked 17th in the world, grabbed three of his six birdies at the 14th, 15th and 16th to pull away for a three-shot win over South Korean Im Sung-jae, who carded a bogey-free 68, and Argentina's Emiliano Grillo, who posted an even par 71.

Chasing Piercy for most of the day after starting five adrift, Finau had finally seized the lead when he got a great break at the par-three 17th, where his tee shot got held up in the rough and stayed just inside the line marking the water hazard.

He gave the ball a little kiss after saving par, and even though he was less lucky at the par-five 18th -- where his tee shot did find the water -- a closing bogey was ultimately irrelevant as his 17-under par total of 267 gave him the win with strokes to spare at TPC Twin Cities in Blaine, Minnesota.

Finau, whose 10 career runner-up finishes include two this season at the Canadian Open and Mexico Open, said it took "really everything I had" to win.

"I was playing great and really every time I looked up it seemed like I was four or five shots back really all day," he said.

He was chasing Piercy, the 43-year-old seeking a fifth PGA Tour title, who started the day with a four-shot lead and was up by as many as five after rolling in birdies of 10 and 30 feet at the second and sixth holes.

The first signs of trouble for Piercy showed with bogeys at the eighth, ninth and 11th.

But the real disaster came late, when he dropped five shots in three holes with a bogey, triple-bogey and bogey at the 13th 14th and 15th.

At 14, Piercy needed two shots to get out of a fairway bunker and when he did, he found the water.

Piercy's five-over 76 left him tied for fourth on 271 alongside fellow Americans James Hahn, who carded a 65, and Tom Hoge, who signed for a 70.

Finau notched his first victory since winning last year's Northern Trust, the first event of the FedEx Cup playoffs.

"I really got things going in the middle of our back nine," said Finau, who drained a 15-foot birdie putt at the 11th. He holed an eight-foot birdie putt at 14, curled in a 32-footer at the 15th and rapped in a nine-footer at 16.

"Once I got control of the golf tournament it was a whole different mindset, trying to seal the deal.

"Couple of squirrely swings coming in, but I called 'bank' on 17 and it worked out."