Kang Sung-hoon earned a two-stroke lead following the opening round of the Shriners Children's Open, where Brooks Koepka featured following the United States' Ryder Cup success.
South Korean golfer Kang carded a 10-under-par 61 to set the early pace in Las Vegas, Nevada on Thursday.
Kang holed an eagle, nine birdies and a bogey to sit atop the leaderboard at TPC Summerlin, where he closed out his round with an eagle putt.
A one-time PGA Tour champion, Kang tied the second-lowest score of his career after the 2019 AT&T Byron Nelson – the scene of his sole triumph on the circuit.
Kang also matched Matt Jones (2021 Honda Classic) for the lowest first-round score on the PGA Tour since the start of the 2020-21 season.
"Last few weeks I wasn't driving it very good, but my iron play was pretty sharp and my putting was pretty good," Kang said. "So I was just thinking if I can get my driver somewhere in play I could actually score better."
Im Sung-jae, Charley Hoffman and Chad Ramey are Kang's nearest rivals at eight under heading into Friday's second round, while Adam Schenk, Talor Gooch, Chesson Hadley, Matt Jones and Matthew Wolff are all seven under.
Defending champion Martin Laird opened his quest for back-to-back titles with a first-round 67.
After helping Team USA to a record-setting Ryder Cup victory over Europe, Koepka kicked off his Shriners Children's Open campaign by shooting a three-under-par 68 to be level alongside the likes of Brandt Snedeker and Will Zalatoris, while Patrick Reed posted a 71 and Rickie Fowler finished the day one over.