Sam Burns pulled five strokes clear at the halfway mark of the Genesis Invitational, while Dustin Johnson is among the chasing pack.
Burns, 24, carded a five-under 66 in the second round at Riviera Country Club in California to surge clear at 12 under on Friday.
Seeking a first PGA Tour win, Burns – who held a two-shot overnight lead – produced a bogey-free second round that included five birdies.
With his total of 130, Burns tied the 36-hole record at the tournament with three players – Davis Love III (1992), Mike Weir (2004) and Shigeki Maruyama (2004).
Johnson, the 2017 champion, is in a four-way tie for second at seven under after shooting a 67.
The two-time major winner recovered from a bogey at the second hole to post five birdies and sit alongside Tyler McCumber (68), Jason Kokrak (68) and Joaquin Niemann (68).
Jordan Spieth continued his good form with a second straight 68 seeing him at six under and in a tie for sixth.
Coming off back-to-back top-five finishes, Spieth is alongside Max Homa (70) and Wyndham Clark (69), while Alex Noren (70), Scott Harrington (66), Cameron Smith (68), Patrick Cantlay (70) and Matt Fitzpatrick (71) are a shot further back.
Brooks Koepka carded a 70 to be at four under, while Rory McIlroy and 2019 runner-up Justin Thomas both missed the cut.
McIlroy missed the weekend at an event for the first time since the 2019 Open Championship after finishing at seven over.