Justin Thomas retained his lead at the Zozo Championship as Jon Rahm surged into contention on Saturday.
After back-to-back 65s at Sherwood Country Club in California, Thomas carded a five-under 67 in the third round.
The American mixed six birdies with just one bogey to get to 19 under and retain his one-stroke lead.
Thomas, a 13-time winner on the PGA Tour, is set for a final-round battle with Rahm.
Rahm charged into outright second thanks to a nine-under 63.
The Spanish world number two capitalised on a fast start, making a 17-footer for eagle at the par-five second hole.
Rahm went bogey-free in his round, which also included seven birdies, to be in contention for a sixth PGA Tour victory.
Of his previous five wins, two have come in the state of California – at the 2017 Farmers Insurance Open and 2018 CareerBuilder Challenge.
Lanto Griffin continued his consistent showing with a four-under 68 that moved him into 17 under and outright third.
Sebastian Munoz (66), Ryan Palmer (66) and Patrick Cantlay (68) are a shot further back.
A group of six players – Webb Simpson (67), Brian Harman (67), Matt Fitzpatrick (67), Bubba Watson (68), Scottie Scheffler (69) and Dylan Frittelli (70) – are at 15 under.
After bouncing back in the second round, Tiger Woods battled in the third, the 15-time major winner and defending champion shooting a 71 to be back at three under.
Rory McIlroy, meanwhile, continued to climb the leaderboard, a 67 lifting him into nine under and a tie for 36th.