American Mark Hubbard ended the first day of the Puerto Rico Open with a one-shot lead after carding an opening 68 in Rio Grande.

Starting on the back nine, Hubbard sank two birdies and a bogey to make the turn in 35 shots, while the front nine proved more fruitful as the 25-year-old PGA Tour rookie came home in 33 shots to lie four under par.

Hubbard's final nine holes included three successive birdies from the fourth and another at the ninth. The only blot in the second half of the world number 394's round was a bogey at the par-three eighth.

"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 on the PGA Tour website.

"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 5-, 6-footers."

Hubbard enjoys a slender lead over compatriots Chris Smith and Billy Mayfair, and Argentinian Emiliano Grillo, who are tied for second on three under after rounds of 69.

Smith and Grillo carded five birdies and two bogeys, while Mayfair recorded six birdies and three bogeys.

They are a shot ahead of an 11-strong group of players on two under, which includes former world number one David Duval, Spaniard Rafael Cabrera Bello and Germany's Alex Cejka.

Zimbabwe's Brendon de Jonge, the tournament's top-ranked player at 87th in the world, is one of 10 players on one under, while two-time major winner John Daly is one of 15 who shot a level-par 72.