JB Holmes leads the Wells Fargo Championship by one shot on 13 under from Martin Flores at Quail Hollow, while Rory McIlroy is seven shots behind Holmes after carding a third-round 65.
Holmes made seven birdies and one bogey to top the leaderboard, with Flores missing the opportunity to share the lead after he bogeyed his final hole to finish on a three-under 69 for the round.
Five-time major winner Phil Mickelson had the best round of the day as the American hit a nine-under 63 to trail Holmes by two shots.
Mickelson made seven birdies and one eagle to put himself in contention heading into the final day.
Former world No.1 McIlroy was one of the early starters on Saturday, with the Northern Irishman tied for 11th and seven shots off the top thanks to a seven-under 65.
"I putted much better," said McIlroy, the 2010 Wells Fargo winner, after rolling in eight birdies to go with a lone bogey.
"I did some work on the putting green last night and I figured out what I need to do out there and it was a really solid round of golf.
"I didn't hit as many loose shots as yesterday. I played solid tee to greens but the real difference today was the putting. I holed more putts."
McIlroy's score could have been better, because he hit a beautiful wedge shot into the par-four 16th, only to watch his ball clatter against the pin and ricochet 18 feet away.
Followed by a huge gallery enjoying the brilliant sunshine, he had a tap-in par at the par-three 17th before getting up-and-down from left of the par-four 18th by sinking an eight-footer.
England's Justin Rose shared fifth place on nine under with Jason Bohn, with Kevin Kisner alone in fourth.
Martin Kaymer was seventh on eight under with Americans Jonathan Byrd and Michael Thompson and Australian Geoff Ogilvy completing the top 10 ahead of McIlroy and co.