Australia's Min Woo Lee shot a three-under 67 to finish six shots behind Highsmith.

Two days after Highsmith made a nervy par putt to just make the cut, he won with the lowest weekend ever at PGA National and is going to the Masters.

Highsmith rallied from a four-shot deficit on Sunday with three-straight birdies around the turn and a 20-foot birdie putt on the par-3 17th which all but clinched it, giving him another six-under 64 to win his first PGA Tour title by two shots.

"Winning was the last thing on my mind," Highsmith said.

"It's incredible to come out on top. I played probably the best round of my life."

Lee finished in a tie for 11th at 13-under, while fellow Aussie Karl Vilips (72) was joint-39th, a further four shots adrift.

Highsmith had a little help from Jake Knapp, who opened the tournament with a 59 and held it together until he put a shot into the water and used two more to get out.

Knapp, trying to become the first wire-to-wire winner in tournament history, had a one-shot lead when his wedge to the 11th came up short and landed in the water. With only half of his golf ball submerged, he tried to blast out, but it trickled down the slope and back to the water. He tried again, this time with the ball holding up in the rough.

"Didn't hit any of them really hard enough, unfortunately," Knapp said.

He wound up with a triple-bogey and never caught up. Knapp (72) tied for sixth along with Michael Kim (71), who played with him in the final group.

Jacob Bridgeman (64) and J.J. Spaun (66) shared second place.

Highsmith, a 24-year-old lefty with a bucket hat and a broad smile, became the first player to make the cut on the number and win since Brandt Snedeker at Torrey Pines in 2016.

With so many players in the mix going into the final round, it was set up to be a wild finish, and five players had at least a share of the lead at one point.

Highsmith is the second first-time winner in as many weeks, following Brian Campbell winning the Mexico Open. Along with earning a place in the Masters and PGA Championship, Highsmith is in the remaining five signature events, starting next week at Bay Hill.

Highsmith shot the lowest 72-hole score since the tournament moved to PGA National, which has held two PGA Championships and a Ryder Cup, in 2007.