Akshay Bhatia shot an opening nine-under-par 63 to take a three-shot lead at the Valero Texas Open in San Antonio.
The American did not drop a shot as he followed four birdies on the front nine with five on the second, including four in his final five holes.
Bhatia sits ahead of Brendon Todd and Justin Lower with Max Homa among a group of four players two shots further back.
Northern Ireland’s Rory McIlroy is tied for eighth on three under par after going bogey free with three birdies.
WHAT RORY HAD TO SAY
The world number two, who recently had a lesson with Tiger Woods’ former coach Butch Harmon, told PGATour.com after his round: “What I’ve been trying to do the last couple weeks is no different than what I’ve been trying to do previously; he just sort of gave me a different way to do it.
“You could tell someone five different things and like for the same feel – like to a piece of a swing, but sometimes none of them resonated, sometimes all of them, sometimes one thing.
“It’s just one of those things over the past few months that nothing was resonating with me.
“He gave me a tiny little something that I went with and, as I said, it’s felt a little better over the last two weeks and felt pretty good out there.”
A win at next week’s Masters will see McIlroy join Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Woods as the only players to have won all four major championships.
Three-time major winner Jordan Spieth had a dour round of 73 salvaged by a hole-in-one on the par three 16th.