Justin Thomas fired another seven-under 65 to grab a one-stroke lead at the halfway mark of the Zozo Championship on Friday.
The American produced a bogey-free second round at Sherwood Country Club in California to move into 14 under.
Thomas, the 2017 US PGA Championship winner, made five birdies on the back nine – his first nine holes – before a solid finish.
The world number three, Thomas has enjoyed a fine year, including winning twice. He has multiple wins in every year since 2017.
Back-to-back 65s have given Thomas a one-stroke lead over Dylan Frittelli and Lanto Griffin, while Patrick Cantlay and Scottie Scheffler are a stroke further back after all four also shot 65s.
The round of the day belonged to Richy Werenski, who broke Tiger Woods' course record with a stunning 11-under 61.
Werenski birdied nine of his first 12 holes after starting his round at the 10th and he picked up another shot at the fifth to put him on track to break 60.
However, a bogey at the par-four sixth hurt his chances, although he responded with birdies at seven and nine to get to 11 under and a tie for sixth.
Abraham Ancer (66), Harris English (67), Bubba Watson (63), Tyrrell Hatton (68), Patrick Reed (63), Tony Finau (64) and Kevin Kisner (67) are all alongside Werenski.
Woods, in action for the first time since the U.S. Open, bounced back from his opening-round 76 with a six-under 66.
Despite his improvement, the defending champion and 15-time major winner is well back at two under to be tied for 66th.
It was a similar story for Rory McIlroy, who carded a 67 to get to four under, although the Northern Irishman is 10 strokes behind Thomas.
Overnight leader Sebastian Munoz dropped back into a tie for 14th after carding a two-under 70.