Rio Grande - Andres Romero, seeking his first PGA Tour win in more than a decade, fired six birdies in a six-under par 66 on Thursday to take the first-round lead in the Puerto Rico Open.
Romero was one shot clear of Austrian rookie Sepp Straka, who had six birdies and one bogey in his 67.
While Romero hasn't won on the US tour since the 2008 Zurich Classic of New Orleans, he captured the European Tour's BMW International Open in 2017.
Although he hadn't cracked the top 20 in two prior events this season, Romero said he had been playing well, and was delighted to see that reflected in his score
"I'm really happy with the round. It's my putting that has been letting me down lately and today it was very good," he said.
"So it gives me a lot of confidence for my whole game."
Straka, a graduate of the Web.com developmental tour, is seeking his first PGA Tour title.
He was one stroke in front of a group of nine players on 68, a group that included Canadian David Hearn.
A group of eight players on 69 included amateur Bryson Nimmer, a Clemson University senior who is making his first PGA Tour start.
D.A. Points, who won the most recent edition of the Puerto Rico Open in 2017 - with 2018's edition cancelled as the island recovered from the devastation of Hurricane Maria - opened with a one-under par 71 in the tournament played opposite the elite WGC-Mexico Championship.
The winner will receive a two-year exemption on the PGA Tour and an exemption to the PGA Championship, but won't get an invitation to the Masters.
Leading first-round scores on Thursday in the PGA Tour Puerto Rico Open at Rio Grande (USA unless noted, a-denotes amateur, par-72):
66 - Andres Romero (ARG)
67 - Sepp Straka (AUT)
68 - Ben Crane, Ollie Schniederjans, David Hearn (CAN), Roberto Castro, Martin Piller, Roberto Daz (MEX), Joey Garber, Nate Lashley, Alex Kang
69 - Martin Flores, a-Bryson Nimmer, Kramer Hickok, David Lingmerth (SWE), Corey Conners (CAN), D.J. Trahan, Brian Davis (ENG), Johnson Wagner