South Korea's Si Woo Kim shot six-under par 66 and claimed a one-shot lead after the third round of The American Express in California as teenager Blades Brown aims for a piece of history.
Kim is at 22-under in a tournament where the players play their first three rounds across three different courses.
Ireland's Seamus Power, who played the Nicklaus Tournament course on Saturday, finished on 13-under after a second consecutive round of 68.
Waterford native Power manager five birdies, including one at the first, before adding two more before the turn. He had his fourth birdie of the day on 11, before dropping a shot on 14.
But Power recovered on the next, the 15th, before finishing out his round with three pars.
Meanwhile, a victory in the tournament would make Brown, 18, the second-youngest champion in a PGA Tour event.
"That to me is a lot of fun. I love environments like that, especially (No.) 17," said Brown.
"There's so many people around it, it gets your adrenaline up. And that's what you play and practice for, right?"
The trio of Kim, Brown and world number one Scottie Scheffler will play in the final group for the last round.
Scheffler and Brown both shot 68s on the Pete Dye Stadium Course, with the duo both one shot behind Kim and tied for second place after sharing the second-round lead.
Scheffler, in his first tournament of the year, scrambled for par on the final hole, with his second shot into the greenside rough. He used a 25-foot par putt to salvage the hole and avoid his second bogey on the back nine.
Brown posted birdies on his final three holes, including a 44-footer on the par-4 18th a day after recording 12-under-par 60 to set a course record on the Nicklaus Tournament Course.
Kim's round at LaQuinta Country Club included seven birdies with a bogey as he bids for his second championship in the tournament, which he won in 2021. He rolled in three straight birdie putts on his back nine.
"Just not thinking about trying to win or trying to finish, just enjoy the round," Kim said. "That's my goal."
Of the top 14 golfers on the leaderboard, the only score at 70 or higher for one round this week was the 72 turned in by Putnam in Thursday's opening round at the Pete Dye Stadium Course.
