Patrick Cantlay rode a blistering start to a record-equalling 10-under par 62 on Thursday and a two-shot lead in the PGA Tour Pebble Beach Pro-Am.
Cantlay took advantage of ideal calm conditions to match the course record at Pebble Beach Golf Links, one of two courses in use for the tournament along with the par-72 Spyglass Hill.
He birdied seven of the first eight holes, draining five-footers for birdies at the first and second and an eight-footer at the third. After a par at the fourth he birdied another four in a row, his approach at the eighth bouncing inches from the cup.
Cantlay added three more birdies coming in, regaining the solo lead with an eight-footer at 17 and getting up and down for birdie at the last for a two-shot lead over 19-year-old American Akshay Bhatia and 33-year-old Henrik Norlander of Sweden.
"I think we got Pebble in pretty much ideal conditions and I don't think it's going to be like that the rest of the week," said Cantlay, who tied the course record shared by Tom Kite and David Duval.
"The greens were good this morning and receptive, and so I hit a lot of good shots just right out of the gate and made everything."
At 11th in the world, Cantlay is the highest-ranked player in the field after the late withdrawal of world number one Dustin Johnson.
If his name atop the leaderboard was to be expected, Bhatia's was a surprise.
The Californian who opted to skip college golf but saw his first pro season disrupted by the coronavirus pandemic, became just the fourth player in the last 25 years to hit all 18 greens in regulation at Pebble Beach.
"Eighteen greens gave me a lot of good looks today," he said. "It's probably the first time I've ever putted this well."
Norlander, who finished with a share of second at Torrey Pines two weeks ago, had nine birdies with one bogey in his 64.
He and Bhatia were one stroke in front of former world number one Jordan Spieth and Nate Lashley.
Spieth, trying to regain the form that earned him three major titles, built on the momentum of his tie for fourth in Phoenix last week with a round that included a hole out for eagle at the 10th along with six birdies and one bogey.
Five players were tied on six-under 66: Russell Knox of Scotland, Tom Lewis of England, Mark Hubbard, Brian Stuard and Will Gordon.
Gordon's was the best round of the day at Spyglass Hill.
Cantlay said he was looking forward to playing Spyglass, "one of my favourite courses out here" before the event returns to Pebble Beach for both weekend rounds in what are expected to be more challenging conditions.
"More of the same," he said of his plan for Friday. "Just hit it really good and take my medicine when I can."
Leading first-round scores on Thursday in the PGA Tour Pebble Beach Pro-Am at Pebble Beach Golf Links and Spyglass Hill (USA unless noted, par-72):
62 - Patrick Cantlay
64 - Akshay Bhatia, Henrik Norlander (SWE)
65 - Nate Lashley, Jordan Spieth
66 - Mark Hubbard, Russell Knox (SCO), Will Gordon, Brian Stuard, Tom Lewis (ENG)
67 - Cameron Tringale, Brian Harman, Matt Jones (AUS), Cameron Percy (AUS), Michael Thompson, Hunter Mahan, Tom Hoge, Vaughn Taylor, Tim Wilkinson (NZL), Daniel Berger, Brandon Hagy