Scott Stallings fired a stunning third round of 63 to surge into a five-shot lead at the Humana Challenge in California.
The American had started play on Saturday one shot off the pace but stormed to the top of the leaderboard thanks to a nine-under-par score on the Nicklaus Private course at PGA West.
Stallings' stunning bogey-free score included a pair of eagles, at the eighth and the 13th, and five birdies as he moved to 22 under for the pro-am tournament.
"I feel good," he said after putting himself in a strong position to claim his third title on the PGA Tour. "I played well. I stayed aggressive. I've been smart when I got out of position.
"I guess you can say it's conservatively aggressive. Like number eight today, I hit a really good drive and had eight iron," he said of his second eagle.
"But just because I had eight iron to a par-five, I fired it in the middle of the green, had a 20-footer and was happy to make it."
A group of five players sit on 17 under, former Open champion Stewart Cink amongst them after managing a round of 66 on the Palmer layout.
He is joined in a tie for second by Americans Roberto Castro (69), who had shared the lead overnight alongside rookie James Hahn, John Rollins (64), Charley Hoffman and Charles Howell III, the latter duo signing for 67s.
Phil Mickelson - a two-time winner of the event - flirted with the cut for much of the day but eventually made sure he would qualify for Sunday after completing a 66 that included six birdies, leaving him on 11 under.
Englishman Ross Fisher also made sure he would play again this week after a birdie-birdie finish meant he managed a 67. He sits on 10 under in his first tournament since becoming a full-time member on the PGA Tour.