Jason Dufner made four birdies in his final six holes to join three others at the top of the leaderboard after the opening round of the CareerBuilder Challenge in California.
The 2013 US PGA champion carded a 64 on the Tournament Course and joins Jerry Kelly, Jeff Overton and Anirban Lahiri on eight-under-par.
Overton enjoyed a run of five successive birdies on the Tournament Course, while Kelly struck five birdies and two eagles on the La Quinta course. India's Lahiri also had his opening round on La Quinta and recorded a bogey-free round.
Those playing on the Stadium Course found it much more difficult, with Canada's Adam Hadwin scoring best with a 66.
Phil Mickelson is four off the lead after a 68 on La Quinta.
