Brooks Koepka will go into the final day of the AT&T Byron Nelson with a two-shot lead from Texas native Jordan Spieth.
While overnight lead Ben Crane struggled on Saturday to drop out of the top 10, Koepka recovered from two bogeys in the first six holes to sign for a 65 which left him clear at the top of the leaderboard.
World number two Spieth has been sat in second place at the end of each round so far but this time was alone in the chase after a round of 67 left him one shot clear of Matt Kuchar, Bud Cauley and Sergio Garcia.
But Crane, who had been top on Friday night after a round of 63, had three bogeys on his way to a disappointing 72 which sent him down into a share of 11th.
"It's probably one of my worst ball-striking performances as a professional." - Brooks Koepka
Koepka got off to an inauspicious start with a bogey on the first. He picked up shots on the third and fifth but fell back to level par when he three-putted the par-four sixth.
However, he responded with back-to-back birdies on the seventh and eighth before picking up three further shots on his way back, and Spieth could not match him as he continued to battle inconsistency.
Koepka was far from happy with his performance on the day, even if he could not complain about the results.
"I putted well today, that's about all I can say," he said on PGATour.com. "It's probably one of my worst ball-striking performances as a professional. Embarrassing after probably the first nine holes but I kept it together. I've got some work to do on the range now.
"Hopefully I can get it straightened out tomorrow, but I'm proud of how I hung in there and just waited through.
Monster putts, a 16-year-old Jordan Spieth, and a fight at the top of the leaderboard. https://t.co/Ye9M0NRHn9
— PGA TOUR (@PGATOUR) May 22, 2016
"Even though I didn't hit it well the course management went really well. The course suits me, so I'll keep doing what I'm doing."
Like Koepka, Spieth has been complaining about his iron play so far, and though the 22-year-old had three birdies on the front nine, he mixed in two bogeys with his two birdies on the way back.
It might have been worse but for a bogey save on the par-four 14th, as he rolled in a long putt from 23 feet after finding the water with his tee shot.
"It was the same thing as the first two days really - further off today on my ball striking but better on the putting," he said.
"Some of the up-and-downs on the front nine were ridiculous and it surprised me I was able to get up and down even though those are shots I practice all the time. There were some really, really tough spots.
"It was a stressful round of golf to play. I just don't have confidence over the ball at the moment. It's very frustrating and pretty incredible that I'm still in the tournament."
