Cameron Young made, by his own count, about a billion feet worth of putts to take the lead after the opening round of the Cadillac Championship.

Young shot a bogey-free eight-under 64 on Thursday for a one-shot lead over Jordan Spieth and Alex Smalley at Trump International Doral to open the $20 million ($A28 million) signature event - the first PGA Tour event at the course in 10 years.

"I think you can be pretty aggressive into a lot of the greens," Young said. "They're not particularly firm. I feel like the ball's sitting when you need it to.

"So, it's more just about avoiding some of the big mistakes."

Young made some putts - about 98 feet worth, to be exact - and his round got rolling with barely any putt at all. He hit his approach from 154 yards to about an inch on the par-4 second, and he went on to make three birdie putts from 25 feet or more before the day was done.

"I feel like I made a billion feet of putts, which I think works most places," Young said. "It's just one of those days that each mistake I made I was not penalised as much as I could have been. And every time my ball got near the hole it seemed to want to go in today."

Spieth chipped in for eagle on the par-5 eighth hole and survived a pair of bogeys on the back nine. He said he relied on notes he took in the Wednesday pro-am - "nerdy stuff" he called it - and generally stayed in control of his round.

"I didn't love some of the swings I made," Spieth said. "But I was able to kind of put them in the right spot and I made some really good swings as well."

World No.1 Scottie Scheffler made three birdies in the first five holes, then didn't get another the rest of the day.

Back-to-back bogeys on Nos.10 and 11 dropped him to one under, and that's where he stayed - with a highlight that might have been a par save on the par-4 14th after he sprayed a driver way right and had the club come out of his hands on the follow-through.

Min Woo Lee (70) is the best-placed Australian in the field, with Adam Scott (76) and Jason Day (77) way off the pace. 

Lee had a double bogey on the last to drop him into a tie for 15th.

Most of this week's field is playing Doral for the first time, at least as pros.

The course held LIV Golf events from 2022 through 2025, but the PGA Tour stopped using the course - a longtime highlight of the Florida Swing - when US president Donald Trump bought the facility.

Scott was the most recent PGA Tour winner at Doral, prevailing in the World Golf Championship-Cadillac Championship in 2016.

His round was two shots worse than Justin Rose - a winner at Doral in 2012.