Patrick Cantlay equalled the course record to claim a two-stroke lead after the first round of a much-changed AT&T Pebble Beach Pro-Am.
The tournament has a very different feel this year, going ahead without celebrities, spectators or world number one Dustin Johnson, who withdrew on Monday, amid the coronavirus pandemic.
But Cantlay set the standard in unconventional circumstances by carding a flawless 10-under-par 62, including seven birdies on the Pebble Beach Golf Links course on Thursday.
Cantlay finished strongly, birdieing the last two holes, to tie the 18-hole record at the iconic Californian links course set by Tom Kite in 1983 and David Duval 1997.
After American teenager Akshay Bhatia and Sweden's Henrik Norlander recorded first-round 64s to go eight under par, three-time PGA Tour champion Cantlay established himself as the leader at 10 under.
Jordan Spieth followed in hot pursuit, the former world number one three shots off the pace as the three-time major champion eyeing his first title since the 2017 Open Championship.
Spieth suffered a final-round slump while leading the Phoenix Open last week but moved on quickly, shooting six birdies and an eagle at hole 10 to claim a share of fourth place alongside Nate Lashley.
Mark Hubbard, Russell Knox, Will Gordon (Spyglass Hill) and Brian Stuard are four strokes off the lead, while the likes of Jason Day, Francesco Molinari and defending champion Nick Taylor are three under.