Wyndham Clark shot a course record 60 to take the lead heading into the final round of the AT&T Pebble Beach Pro Am.
The US Open champion made five putts of at least 25 feet in his 12-under-par round with two eagles, nine birdies and one bogey, eclipsing the previous record of 62.
Sweden's Ludvig Aberg continued his strong tournament with a five-under-par 67 to sit one shot off the lead with France's Matthieu Pavon a further shot behind as he chases a second successive victory on tour.
Australian Jason Day, back to something approaching his best form, also caught the eye with a fantastic round of 63 that left him in and around the top half-dozen players on the leaderboard.
Seamus Power shot a four-under par 68, his lowest of the week, to reach seven-undr par and tied-31st.
Rory McIlroy, meanwhile, who never recovered from the two-shot penalty on Round 1, carded a 69 to sit on two-under-par, alongside Americans Grayson Murray and Max Homa in 66th position.
Course record and career low at iconic Pebble Beach.
— PGA TOUR (@PGATOUR) February 3, 2024
Not a bad day to be @Wyndham_Clark. pic.twitter.com/5Sc9Wjxusu
Third round leader Clark, who had a lengthy eagle putt at the last to break 60, said he had a "really good feel on the greens".
He said: "I was just, 'See ball, hit ball, try to hit it where I wanted to'.
"So in my mind I was like, 'All right, let's just get us to where we're putting,' because the hole seemed like a bucket today."
Clark's round does count as a course record on the PGA Tour, despite the players being able to clean and place balls on the fairways.
