Sebastian Munoz set the early pace at the Zozo Championship after earning a one-stroke lead in the opening round, while defending champion Tiger Woods struggled on his return to the PGA Tour.
Colombian golfer Munoz carded an eight-under-par 64 to top the leaderboard in Thousand Oaks, where the tournament is taking place after being relocated from Japan due to the coronavirus pandemic and travel restrictions.
Munoz – eyeing his second Tour title – holed two eagles, eight birdies, a double bogey and two bogeys at Sherwood Country Club.
The 27-year-old recorded his second eagle of the day on the par-five 16th, holing out from 51 yards to mark the third instance in his Tour career with two eagles in a single round.
England's Tyrrell Hatton and American star Justin Thomas – who ended the day eagle-birdie-birdie – are a shot off the pace heading into Friday's second round, while Brian Harman, Lanto Griffin, Kevin Kisner, Harris English and Dylan Frittelli are stroke further back at six under.
World number two Jon Rahm and Jason Day were among the players to post first-round 68s in a field missing top-ranked golfer Dustin Johnson and Adam Scott due to positive coronavirus cases.
After claiming his maiden Tour title via last week's CJ Cup at Shadow Creek, Jason Kokrak shot a three-under-par 69 to be tied for 26th alongside the likes of Xander Schauffele and Matthew Wolff.
Searching for his first victory since 2017, former world number one Jordan Spieth opened with a 70, just like 2018 Masters champion Patrick Reed.
Rory McIlroy – a four-time major champion – recorded a one-over-par 73, a shot worse off than Phil Mickelson.
As for Woods, his title defence and bid for a record-breaking 83rd Tour crown started with a forgettable four-over-par 76 that left him 12 strokes behind Munoz.
Making just his eighth start of 2020 and playing for the first time since missing the U.S. Open cut ahead of next month's Masters defence, Woods played three par-five holes over par in the same round for the first time in his illustrious career.
Woods carded a three-over 39 on the back nine, which included a double bogey and two bogeys to go with a solitary birdie.