Russell Henley continued his stunning start to life on the PGA Tour as he fired an opening eight-under 64 at the Humana Challenge in California.
The rookie, who birdied the last five holes to win the Sony Open in Hawaii last week, carded an eagle, seven birdies and just one bogey on the Nicklaus Private course at La Quinta.
Henley maintained his momentum of last week and birdied five of his first seven holes after starting at the 10th, although he gave a shot back at 17.
But the 23-year-old hit back with an eagle at the fourth, and further birdies at the fifth and eighth holes moved him to within one shot of the lead.
Roberto Castro, Jason Kokrak and James Hahn all returned bogey-free 63s to share the lead after the first day of the popular pro-am tournament.
Kokrak's round at La Quinta included two eagles, while Hahn was eight under after only 12 holes on the PGA West layout before his hopes of a 59 vanished with a run of five pars.
Greg Chalmers and Doug LaBelle also carded a pair of eagles each as they joined Henley on eight under, but Phil Mickelson struggled on his seasonal debut.
The four-time major champion failed to take advantage of the friendly scoring conditions as he laboured to a 72 on a day in which 121 of the 156-strong field broke par.
Henley said: "It was a perfect day. The weather is perfect, the greens were true so it's just trying to stay patient and let the birdies come to me. And I made some good putts.
"I got off to a fast start. Hit the pin on the first hole for eagle and it went to about two feet. So it was cool to start out with a birdie. That gave me a little confidence and I just fed on it all day."