The only person who gave Cameron Young any trouble in the final round of the Cadillac Championship was, well, Cameron Young.

He called a one-stroke penalty on himself while playing the par-4 second hole, after he caused his ball to move in the fairway. And then he made par anyway.

Young went wire-to-wire with a final round of four-under 68 getting him to 19 under for the week and six shots clear of world No.1 Scottie Scheffler (68), who finished second for the third consecutive start.

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

Ben Griffin (68) was third at 12 under, while Australian Adam Scott (64), Si Woo Kim (70) and Sepp Straka (66) tied for fourth at 11 under.

Scott likely clinched a spot in the US Open — which would be his 100th consecutive major start, assuming he starts in the PGA Championship later this month — after shooting 66-64 on the weekend.

"To win a major I'm going to need to put four days together, not just a weekend coming from behind," said Queenslander Scott, who was the winner of the World Golf Championships Cadillac Championship — until this week, the most recent PGA Tour event at Doral — in 2016.

"I feel like my game is there. I'm doing all the things that I think I need to do to be in that kind of contention."

Compatriots Min Woo Lee and Jason Day both shot 68s to finish seven and four under respectively.

With US President Donald Trump in place to watch most of the round at Trump National Doral, Young picked up $US3.6 million ($A5 million) for the second-biggest payday of his career. He made $US4.5 million ($A6.2 million) earlier this year for winning The Players Championship.

A bit more than an inch of rain fell on the course in the early morning, delaying the final round by two hours, and the Blue Monster was no longer a monster.

The average scores in the first three rounds were between 71 and 71.6. The average score on Sunday (Monday AEST), with preferred lies, was 69. There were nine birdies — total — on the par 18th in the first three rounds and 12 at the finishing hole on Sunday alone.

Young called the violation on himself with his ball in the middle of the fairway on the second hole — it moved at address, something he said has happened to him before — and said he didn't hesitate to do the right thing.

"Your heart sinks when you see it move," Young said.

"But it moved. That's part of what's golf about. There's no one who's going to give me a penalty there but myself."

With AAP.