Young has made only three cuts in 12 starts, most recently, last week at the Honda Classic.

He shared the 18-hole lead at PGA National and finished in a tie for 29th, his best finish of the season. The 28-year-old from South Carolina found Grand Reserve to his liking on Thursday.

He made two eagles on the front nine, then expanded his lead with a third eagle on the par-5 15th by hitting 3-wood to about 10 feet.

"I had about 255 (yards), straight into the wind, trees in front of me," Young said. "The wind was so strong I decided to just hit this high, draw 3-wood over the trees and I flushed it. That was a pretty special shot."

Young has a three-shot lead over Max McGreevy and Akshay Bhatia, the 21-year-old who regularly plays on the Korn Ferry Tour.

Young made his PGA Tour debut in the Puerto Rico Open two years ago, missing the cut.

"At least I've seen this course, whereas the West Coast swing it was a bunch of courses that I've never seen and a bunch of practice rounds." - Carson Young.

But at least he had some experience. His other 12 starts on tour this season were on courses he hadn't played, and four of the tournaments were held on multiple courses.

"At least I've seen this course, whereas the West Coast swing it was a bunch of courses that I've never seen and a bunch of practice rounds," Young said.

"It was nice to be on the East Coast again with the Bermuda grass, which is what I'm used to."

Bill Haas and Scott Piercy were among those at 67, while former PGA champion Jason Dufner was part of the group at 68.

Australians Geoff Ogilvy and Greg Chalmers are among a group of 12 tied for 16th after shooting 69.

The Puerto Rico Open is held opposite the Arnold Palmer Invitational, where every PGA Tour member from the top-50 in the world ranking is playing.

The winner gets a two-year exemption on the PGA Tour, along with a spot in the PGA Championship. It does not come with a Masters invitation.

Ryan Brehm won last year and has spent the last month or so playing in $US20 million ($A30 million) tournaments at Phoenix, Riviera and Bay Hill.