Jason Dufner, who is chasing his first USPGA Tour win in 163 starts, extended his lead to two shots after firing a five-under 67 in the third round of the Zurich Classic.
American Dufner moved to 17-under par 199, two strokes ahead of Canadian Graham DeLaet who soared into contention with a six-under 66 for 201.
"Got off to a really nice start there ... kind of nice on this course," Dufner said.
"Couple of the holes are some of the tougher ones on the golf course so that kind of gets you in a little bit more comfortable mindset for the day."
South African Ernie Els (68) and American John Rollins (69) were tied for third on 14-under 202.
Dufner has struggled to hold 54-hole leads in the past. He led heading into the final round of the 2011 PGA Championship but lost in a playoff to Keegan Bradley.
"I hadn't played as well as I would like on the weekends, I have tried to identify some of the reasons why and will try to implement some of those tomorrow," said Dufner, who also lost in a playoff last year at the Phoenix Open to Mark Wilson.
"Right now a win would be great. Obviously I've been be knocking on the door with a lot of solid rounds, lot of solid play last year and at the end of the year."
Dufner, who turned 35 last month, finished with six birdies and one bogey on the TPC Louisiana.
He got off to a quick start Saturday, making birdie on three of the first five holes. He rolled in putts of 50-feet and 20-feet the par-four fourth and par-four fifth.
His only blemish of the day was making bogey on the par-four sixth but he rebounded on the next hole with a birdie on a par-five. He added two more birdies on the back nine on Nos. 15 and 18.
DeLaet shot his lowest round since firing a 63 in the opening round of the Sony Open. Before the Sony, he sat out half a year while recovering from back surgery. DeLaet played just twice on the tour in 2011, making the cut at the St. Jude Classic but finishing in a tie for 73rd.
"It's exciting," said DeLaet. "It's the first time I've been in this position this deep into a tournament. I'm looking forward to the challenge."
Ryan Palmer tied the course record with a 64, becoming the third player to shoot the score this week.
He was tied for fifth on 13-under 203 with Cameron Tringale (68) and Steve Stricker (69).
Masters winner and defending champion Bubba Watson also rocketted up the leaderboard with a seven-under 65. Watson, who made the cut by one stroke on Friday, has a share of 16th place at nine-under.
In a span of just two days, Watson went from saying he wished he was at home with his family to giving himself an outside chance at a victory.
"I'm tied for 15th (actually 16th)," Watson said. "So long as I don't choke tomorrow, I should have a good shot at it."
England's Luke Donald (66) was 12-under and tied for eighth with Ken Duke (71). Donald needs a solo finish of seventh or better to regain the first spot in the World Golf Rankings.