Will Gordon shot four straight birdies on his way to holding a one-stroke lead from Russell Henley on the opening day at the PGA World Wide Technology Championship at Mayakoba on Thursday.
Gordon, who lost his PGA Tour card in his rookie season two years ago, shot a nine-under-par 62 including an eagle on the par-five fifth hole at El Camaleon Golf Club in Riviera Maya, Mexico.
Henley is eight under, having also peeled off four consecutive birdies from the 10th to the 13th holes, while he finished his round with two more birdies to edge into second behind Gordon.
Scott Piercy, Francesco Molinari, Harris English and Sam Ryder are all one further stroke behind at seven under.
Viktor Hovland, who is chasing a third straight Mayakoba crown, is six under alongside Scottie Scheffler, who is hoping to re-claim the world number one ranking from Rory McIlroy.
The two-time Mayakoba champion started with two bogeys in his first eight holes, but rallied with four birdies before an eagle firmly put him in contention. Scheffler had less drama in his bogey-free round, with five birdies.
Another former Mayakoba winner, Matt Kuchar, put together four straight birdies from the fourth to the seventh holes, but is five under with two bogeys stalling his progress.
One of the pre-tournament favourites, two-time major winner Collin Morikawa, struggled with four bogeys for an opening-day even-par 71 to be nine shots off the pace.
Tony Finau is three under, fighting back with four birdies on a bogey-free back nine after a triple bogey on the second hole.