Grayson Murray missed out on the chance for a sole first-round lead at the American Express in California after his 23-foot putt failed to find the ninth hole.
Starting on the back nine, American Murray strung together four birdies and reached the turn on a six-under 30.
Three more birdies followed, but the ninth was the sole blot on his book and saw him finish on eight under and tied for first with compatriot Zac Blair.
Amateurs compete alongside the pros at the tournament formerly called the Desert Classic, with one-armed Canadian Laurent Hurtubise making his mark after carding a hole-in-one on the fourth and throwing off his cap in celebration.
Three players – Hank Lebioda, former Masters runner-up Rickie Fowler and Scottie Scheffler – sit on seven under and tied for third, with a pack of eight sitting a shot further back, including Scotland’s Russell Knox.
Reigning champion Adam Long started his defence with a 69, mixing two bogeys with four birdies on his opening nine and picking up shots on the par-four 16th and 18th for a share of 49th place.