PGA Tour rookie Mark Hubbard carded a four-under-par 68 for a one-shot lead at the close of round one at the Puerto Rico Open on Thursday.
Hubbard, who earned a tour card after finishing inside the top 25 on the Web.com Tour last season, holed six birdies and two bogeys in a solid start to proceedings at the Trump International Golf Course.
The 25-year-old American holds a slender advantage over compatriots Chris Smith and Billy Mayfair and Argentinean Emiliano Grillo.
"It played tough out there with the wind, but I hit a lot of really good kind of three-quarter and half shots into the wind," Hubbard said.
"I actually probably played the into the wind holes better than the downwind holes where I had to just hit normal shots. But I drove it pretty well, kept it in the fairway and made a lot of solid five-, six-footers."
While the top 50 players in the rankings contest the WGC-Cadillac Championship, the lesser lights took to the course in Rio Grande and Hubbard came up trumps on day one.
Starting on the back nine, Hubbard had a bogey sandwiched in between two birdies before the turn.
Hubbard, who hit the headlines when he proposed to his long-time girlfriend on the 18th green at the Pebble Beach National Pro-Am in February, stepped it up a gear on the front nine with a flurry of three birdies starting at the fourth hole.
He dropped a shot at the penultimate eighth hole but responded immediately with a birdie to top the leaderboard heading into day two.
There is a logjam for fifth spot, with a total of 11 players two shots off the pace.
Dicky Pride, Alex Cejka, Rod Pampling, JJ Henry, David Duval, Rafael Cabrera Bello, James Driscoll, Jonathan Byrd, Chad Collins, Scott Pinckney and Jon Curran all carded 70s.
Defending champion Chesson Hadley is a shot further back, while Jarrod Lyle ended the day four over in his fifth tour start this season after beating cancer for a second time.