Andrew Landry carded a seven-under-par 65 to take a one-shot lead at the CareerBuilder Challenge following Friday's second round.
Playing the year's first PGA Tour event on the mainland, Landry birdied five of his last eight holes to take the lead entering the weekend at 16 under.
The American has not yet made a bogey this week as he leapfrogged Jon Rahm atop the leaderboard.
Spanish star and world number three Rahm finished round two just one shot back after firing a 67.
Rahm already has a runner-up finish this year. He had two early bogeys on Friday, but settled down on the back nine.
Jason Kokrak ended the second round in third place at 14 under following his 69 after his impressive nine under opening round.
"I worked with my coach and was struggling in a practice round on Wednesday," Kokrak said Friday. "My legs get a little bit too jumpy and move around a lot. So we worked on that and I started hitting the ball pretty good and I'm just trusting it out there.
"I've given myself a lot of close opportunities. I rolled the putter very well [Thursday] and [Friday] didn't make quite as many, but still gave myself a lot of chances."
Zach Johnson surged up the leaderboard with an eight-under 64. The two-time major champion had six birdies on his back nine to climb into a tie for fourth at 13 under alongside Michael Kim (64) and Martin Piller (67).
Brian Harman, in search of his sixth straight top-eight finish, shot a four-under 68 to remain in the hunt at 11 under.
He had just one bogey on day two, but did not give himself as many birdie opportunities as he did on Thursday.
Defending champion Hudson Swarfford (68) is six shots off the pace heading into Saturday's third round, while two-time Masters winner Bubba Watson (71) is three under.
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