Charley Hoffman fired five birdies in a five-under par 65 to break free atop a crowded leaderboard at the US PGA Tour Charles Schwab Challenge, where world No 1 Scottie Scheffler struggled.
Hoffman had a one-stroke lead over five players at Colonial Country Club in Fort Worth, Texas, where Kim Seong-Hyeon, Martin Laird, Davis Riley, Brian Harman and Tony Finau were all in the clubhouse on four-under before Hoffman rolled in a 34-foot birdie at the 13th for the solo lead.
Hoffman, chasing a fifth PGA Tour victory but his first since the 2016 Texas Open, had opened with a two-putt birdie at the par-five first and added birdies at the third, eighth and 11th.
"It was weirdly, like, easy," Hoffman said. "I didn't really put myself in any bad positions out there, hit a lot of fairways, hit a lot of centre of the greens and had putts for birdies, which is nice.
"Which usually, I would say, is not my MO," added Hoffman. "But I saw the scores out there not going too low, I knew I didn't have to be too aggressive."
Another 14 players were just two shots off the lead on 67, a group headlined by two-time major-winner Collin Morikawa.
But Scheffler, who is facing multiple charges stemming from a traffic incident at the PGA Championship in Louisville, Kentucky, last week, was well adrift on two-over par 72.
The 27-year-old American, who put together a run of four wins in five events including a second Masters title in April, found the water on the way to a triple-bogey six at the par-three 13th.
He finished the day with a pair of bogeys and three birdies – the last an 12-footer to claw back a shot at the 17th.
Scheffler's effort came on the same day that police in Louisville announced that the detective who arrested him last Friday had been reprimanded for not turning on his body-worn camera during the arrest.
However, Scheffler is facing arraignment on June 3 on charges of felony assault of a police officer, criminal mischief, reckless driving and disregarding signals from an officer directing traffic in the incident, in which he allegedly tried to go around a traffic jam as police investigated an earlier fatal accident.
Among the group sharing second, South Korea's Kim hit his second shot at the par-five first – his 11th hole of the day – within four feet for eagle.
Scotland's Laird birdied 15, 16, 17 and 18 to surge up the leaderboard. Reigning Open champion Harmon also had four birdies while Riley and Finau both had five birdies and one bogey – Finau launching his day with a 56-foot birdie putt at the 10th.