Jason Dufner birdied four of his final six holes to join a four-way tie for the lead after the opening round of the CareerBuilder Challenge.
The former Ryder Cup player posted a blemish-free 64 to join Anirban Lahiri, Jeff Overton and Jerry Kelly at the top of the leaderboard after a day of low scoring in California, where Phil Mickelson was making his return to action after a three month lay-off.
With the event being held across three courses, Dufner opened with back-to-back birdies on the Tournament Course on his way to reaching the turn in 32, before following gains at the sixth and seventh by picking up another stroke at the par-four ninth.
Overton fired five straight gains along the front nine to also post an opening 64, while Lahiri's bogey-free start and Kelly's low round came on the Tournament Course.
"I kept it in play all day and I think that's pretty neat to do around a course like La Quinta," Lahiri said. "I'm pretty happy with the way I hit it off the tee and didn't miss a green - so that usually does it for you."
Colt Knost and Jamie Lovemark lie one off the pace while Canada's Adam Hadwin is part of an 11-way tie for seventh after his round-of-the-day 66 on the Stadium Course.
Defending champion Bill Haas sunk an opening-hole eagle on his way to six under at La Quinta, while Mickelson began with a four-under 68 in his first start since October's Presidents Cup.
"It was a fun start to the year," Mickelson said "It was fun to get back in the swing of it. I had a good, solid round and it was a good way to start."
Watch the CareerBuilder Challenge throughout the week live on Sky Sports 4 - your home of golf. Featured group coverage begins on Friday from 4.30pm on SS4 red button and Sky Sports Xtra.