Los Angeles - Spain's Jon Rahm fired a 10-under par 62 on Thursday to seize a one-stroke lead in the first round of the US PGA Tour CareerBuilder Challenge in La Quinta, California.
Rahm, the highest-ranked player in the field at number three in the world, sizzled on the La Quinta Country Club course - one of three in use over the first three rounds - with eight birdies and an eagle.
He was one stroke in front of Americans Austin Cook, Jason Kokrak and Andrew Landry.
It was a further stroke back to Brandon Harkins, Martin Piller, Beau Hossler and Aaron Wise.
With back-to-back birdies to start, an eagle at the par-five fifth and birdies at six and seven Rahm was six-under through his first seven holes.
He couldn't help but remember Canadian Adam Hadwin's 59 on the La Quinta course last year.
"Any time you have that going for you, you get thoughts come in your head, 60, maybe 59," Rahm said. "I knew that if I kept playing good I was going to have more birdie opportunities, and I tried not to get ahead of myself."
Although he couldn't break 60, Rahm was pleased with the lowest round of his career on the PGA Tour.
"That's golf," said Rahm, who picked up four more birdies coming in. "You're not going to make every single putt, you're not going to hit every shot perfect. I birdied the last hole, had a couple of great sand saves coming in, shot 10-under par.
"There's not much more I can ask for," added Rahm, who hit 12 of 14 fairways and 15 of 18 greens in regulation and needed 25 putts.
Kokrak seized his share of second by playing his last five holes, the fifth through ninth at La Quinta, in five-under par, with three birdies and an eagle.
Landry had five birdies and an eagle on his outward run at La Quinta and picked up two more birdies coming in while Cook fired seven birdies and an eagle on the Nicklaus Tournament course.
Five-time major-winner Phil Mickelson making his first start since the WGC-HSBC Champions in October, got off to a fast start with four birdies in his first six holes at La Quinta.
But Mickelson had three bogeys and just one more birdie the rest of the way, capping his round with a bogey at the par-four 18th.
"It was fun to get back out and be competitive," Mickelson said. "I for some reason am stuck on 70 here at La Quinta, whether I get off to a good start or a bad one I end up shooting the same score."
Leading first-round scores on Thursday in the US PGA Tour CareerBuilder Challenge, played on the La Quinta Country Club, Nicklaus Tournament and Stadium Course at La Quinta, California (USA unless noted, par-72)
62 - Jon Rahm (ESP)
63 - Austin Cook, Jason Kokrak, Andrew Landry
64 - Brandon Harkins, Martin Piller, Beau Hossler, Aaron Wise
65 - Wesley Bryan, Nick Watney, Talor Gooch, Jhonattan Vegas (VEN), Brian Harman, Grayson Murray
66 - Lucas Glover, Alex Cejka (GER) Colt Knost, Matt Every, Kevin Na, Adam Hadwin (CAN), Hudson Swafford, Maverick McNealy
67 - Richy Werenski, Harris English, Zach Johnson, Kevin Streelman, Matt Atkins, Sam Ryder, Conrad Shindler, Rob Oppenheim, Nate Lashley, Charles Howell, Ben Silverman (CAN), Jonathan Byrd, Kevin Kisner, Daniel Summerhays, C.T. Pan (TPE), Bud Cauley, Michael Kim, Chez Reavie, Dou Zecheng (CHN)