Chris Kirk's hot start propeled him to a five-under-par 65 on Friday and a one-stroke halfway lead in the US PGA Tour Sony Open over rookie Taylor Montgomery and J.J. Spaun.
Kirk, who shared the overnight lead with Montgomery and three-time major winner Jordan Spieth, opened with three birdies on the par-70 Waialae Country Club course in Honolulu, Hawaii.
After a bogey at the sixth he added three birdies coming in, capping his round with a two-putt birdie at the par-five 18th for an 11-under par total of 129.
Montgomery stayed in range with a four-under-par 66 and Spaun joined him on 130 with a 64.
But Spieth carded a five-over-par 75 that featured six bogeys -- including four in a row from the eighth through the 11th.
Although darkness halted play with a handful of players still on the course, Spieth was destined to miss the cut.
He'll be just the sixth player in the past 10 PGA Tour seasons to miss the cut after holding a share of the first-round lead.
"Just a bad day," Spieth said. "Didn't feel like it was much different. Made a couple bad swings from off the tee.
"Other than that, I didn't play that different. I just ended up a foot into the rough here, right behind a tree here, it was a weird, weird day."
In contrast, Kirk's day could hardly have gone better.
"I felt good going into today and after playing really well yesterday you want to come out and hit some solid shots and kind of ease into it," he said.
"I did not ease into it at all. Really nice putt I made on one, and then couple pitching wedges on two and three that I hit pretty close."
He needed a good par save at the fifth and was in the rough off the tee on the way to his bogey at the sixth, but made three more birdies on the back nine and was "never really in any kind of stress."
Kirk, who took a break from the sport in 2019 to deal with alcohol abuse and depression, is chasing a fifth US PGA Tour title, but his first since Colonial in 2015.
He said he's relishing the challenge of trying to return to the winner's circle.
"It's so difficult to be great at this game professionally in the mental side," he said. "I think that I definitely always remind myself that pressure is a privilege when you start feeling a little bit of nerves."
Spaun was briefly atop the leaderboard after his seventh birdie of the day, a 13-footer at the seventh hole, moved him to 11-under. But he bogeyed his final hole, the par-five ninth.
"Just one bad swing," said Spaun. "I'm in a good spot going into tomorrow and the weekend."
Spaun is chasing a second US PGA Tour title after winning the Texas Open last season. Montgomery, a rookie who enjoyed a strong fall swing, is chasing his first.
"I definitely feel like I could win at any time," he said. "I hope to do that soon."