MIAMI (AFP) — World No. 4 Cameron Young cruised through Sunday's final round despite a penalty to win the Cadillac Championship by six strokes, taking his third career PGA Tour triumph.

The 28-year-old American called a penalty on himself in the second fairway when he saw the ball move then salvaged par on his way to firing a four-under par 68.

He finished 72 holes on 19-under 269 for the $3.6-million top prize at Trump National Doral.

Young became only the third wire-to-wire winner at Doral, the first since Andy Bean in 1977.

"When the golf course is difficult, when the playing conditions are difficult, that tends to make it easier for me mentally," Young said.

"That's a big part of keeping yourself in it out here... thankfully I was able to stay where my feet were and hit a bunch of good shots."

Young, who turns 29 on Thursday, won his first PGA title last August at Greensboro, captured the Players Championship in March and shared third last month at the Masters.

His six-stroke victory margin matched the largest ever in a PGA event at Doral, a feat last managed by Hubert Green in 1976.

"The self-belief just continues to build," Young said.

"I put myself in plenty of good places over the course of the last four or five years and recently have started to come out on the better side of it so excited for the next few weeks."

More than an inch of rain fell overnight, delaying the final round of the $20 million signature event after softening the Blue Monster course.

US President Donald Trump watched Young sink his final putt from a suite at the 18th hole.

Top-ranked Scottie Scheffler birdied three of the last four holes to shoot 68 and finish second on 275, one stroke ahead of fellow American Ben Griffin.

It was the third consecutive runner-up finish for Scheffler after placing second at the Masters and Heritage tournaments last month. Not since 2014 had one player managed three PGA runner-up efforts in a row.

The result came in Scheffler's final tune-up before defending his PGA Championship title in two weeks at Aronimink.

Australian Adam Scott fired a 64 to share fourth on 277 with Austrian Sepp Straka, who shot 66, and South Korean Kim Si-woo, who closed with a 70.

After calling the penalty on himself at the second Young hit his approach to 13 feet and sank the clutch par putt to regain momentum.

"Your heart sinks when you see (the ball) move, but it moved and that's part of what golf is about," Young said. "There's no one that was going to give me a penalty there but myself.”

"I've had about four of those on the PGA Tour now, so I need to start setting the club down a little softer, but it's just one of those times. How was I going to look the other way and say it didn't move when it rolled over and went an inch forward?”