American Robert Garrigus shot a second consecutive 66 to take over from Lee Westwood at the top of the leaderboard after the third round of the St Jude Classic in Memphis.
Garrigus picked up four birdies and an eagle at the par five 16th but also had two bogeys to lie on 11 under par, two shots clear of Robert Karlsson of Sweden, who shot a 68 at TPC Southwind.
Heath Slocum also shot a 66 to lie third on eight under, level with England's Westwood who had to settle for a one over 71 in his third round.
Karlsson had five birdies to three bogeys, while American Slocum did not drop a shot as he carded four birdies, including two in his last three holes.
World Number Three Westwood, who fired a 63 in the opening round and claimed three birdies on his last three holes to rescue his second round, did not fare so well this time.
He picked up three shots but made four bogeys.
Westwood, who picked up a third birdie on the 16th only to drop his fourth shot of the day on the very next hole, insisted he was still well-placed going into the final round.
"I'm only three back so anything can happen," Westwood said.
Four Americans - Shaun Micheel, Tim Petrovic, Lee Janzen and Garrett Willis - lay on six under in a tie for fourth.
Northern Ireland's Rory McIlroy, the World Number Ten, lost ground on the leaders, a 72 sending him back to three under, while Irishman Padraig Harrington lay on level par overall after a 71.
