For now, the world's top-ranked player is chasing a leaderboard that includes Brooks Koepka; the five-time major champion looking for his first victory since returning to the PGA Tour from LIV Golf.

Koepka shot an eight-under 63 on Thursday and trailed first-round leader Taylor Moore by one at the revamped TPC Craig Ranch, while playing with Scheffler (66) and Si Woo Kim (64).

"I felt like I was getting lapped out there for a little bit," said Scheffler, who led from the start of last year's Nelson and won by eight shots at 31-under while tying the tour's 72-hole scoring record at 253.

"So I was fortunate to make a couple birdies late in the round and keep myself in the tournament."

Moore, whose only win in his first 128 tour starts came at the 2023 Valspar Championship, made a 14-foot birdie putt from the fringe on the par-5 ninth to finish the best round of his tour career.

The Texas native and Oklahoma resident leads Koepka and Jesper Svensson, who had a chance to join Moore atop the leaderboard, but missed a nine-footer on the ninth.

Kim, the highest-ranked player in the field behind Scheffler at No.24, had the only bogey in the threesome, on his 16th hole at the par-3 seventh.

One of several countrymen in the event sponsored by South Korean conglomerate CJ Group, Kim closed the gap on Koepka with a birdie at the ninth while Koepka settled for par.

Emiliano Grillo, Keith Mitchell, Stephan Jaeger, Michael Thorbjornsen, Tyler Duncan and Kensei Hirata were tied with Kim.

Doug Ghim was at 65 with Mackenzie Hughes, Hank Lebioda, Austin Eckroat and Lanto Griffin.

Koepka, who contended at last week's PGA Championship before fading Sunday, eagled the par-5 12th and was four-under through five holes. He had four more birdies in a span of five holes in his back nine, capped by a three-foot birdie putt on the short par-4 sixth.

Kim had four birdies on the front and four more on the back, while Scheffler was lagging at two under before getting birdies on three of his final five holes. 

"It was just a comfortable group," Koepka said. "Everyone is just kind of feeding off each other, easy. Everyone's having fun. Makes it enjoyable. I feel comfortable on the golf course as well."

Australians Karl Vilips (70) and Cam Davis (74 ) are at one-under and three-over respectively.