Charley Hoffman, seeking his first US PGA Tour win in three years, fired a five-under par 66 to seize a two-shot lead after three rounds of the $5.8 million Heritage tournament.
Hoffman played without a bogey on Saturday to build a 54-hole total of 11-under 202. He was two shots in front of fellow American Webb Simpson, who carded a 65 for 204.
Hoffman, Steve LeBrun and Kevin Streelman had shared the 36-hole lead after the rain-disrupted second round concluded on Saturday morning. A record-tying 91 players made the halfway cut.
Once the third round got underway, Hoffman was on the move. He birdied four of his first five holes, and ended up needing just 21 putts in the round as he put himself in position to nab a third career tour title and his first since 2010 in Boston.
Simpson, the US Open champion who missed the cut at the Masters, notched the lowest score of the third round to climb up the leaderboard.
Streelman was in third place after a 69 for an eight-under total of 205. It was a further stroke back to Zimbabwe's Brendon de Jonge (67) and Northern Ireland's Graeme McDowell (68) on 206.
Simpson, who hasn't won since his US Open triumph last year, had six birdies and no bogeys.
"It's all in my swing," said Simpson, who hit 15 greens in regulation.
"We've been working on the same thing all year. We knew where we wanted to get, we just didn't know how to work on it. Once we found out how to work on it, everything clicked."