Harris English carded a bogey free 65 to maintain his two shot advantage after 54 holes as he looks for a first World Golf Championships title at the WGC-FedEx St Jude Invitational.
The American led by two after rounds one and two at TPC Southwind but he was caught at the top of the leaderboard in round three as Major Champion Bryson DeChambeau signed for a 63 to get to 16 under.
English responded in fine fashion, keeping his cool to birdie two of his last three holes and move to 18 under as he seeks a wire to wire victory in Memphis.
Australian Cameron Smith carded a 65 to sit alongside DeChambeau, two shots clear of Mexico's Abraham Ancer, who endured late slips in his 67.
England's Ian Poulter was then at 13 under alongside American Scottie Scheffler, two shots clear of former World Number One Dustin Johnson, American Will Zalatoris, England's Paul Casey and South African Louis Oosthuizen.
English won this event in 2013 for his maiden US PGA Tour victory and has since taken that tally to four with two this season.
He has yet to win on the European Tour but a victory on Sunday would make him the fourth wire to wire winner of the 2021 Race to Dubai after Bernd Wiesberger, Lucas Herbert and Nacho Elvira.
"There's a lot of good players behind me and my goal is just stick to my strategy and execute and whatever happens, happens," he said. "I can't control what everybody else is doing.
"Eight years ago was really my first time getting in the mix and having a chance to win a tournament coming down the stretch. It's been fun. I really don't shy away from it, I enjoy it."
Ancer hit the pin with his approach at the second and holed from inside two feet before birdieing the par five next with two putts from the fringe.
That had him in a share of the lead and he briefly led on his own when he put his second to the ninth to seven feet to turn in 32 but English, after a slightly ragged start, holed from 23 feet on the eighth to join him.
There's a lot of good players behind me and my goal is just stick to my strategy and execute and whatever happens, happens
That seemed to spark English into life and he put an approach to two feet at the ninth but Ancer would not be held off and he holed a 13 footer at the tenth to get to 15 under.
It was soon to be a three way tie as DeChambeau caught fire on the back nine after turning in 33.
The 27-year-old had sandwiched a two putt birdie on the third with smart approaches into the second and fifth but then dropped a shot on the next.
A second to six feet at the tenth seemed to kickstart his round, however, and he left himself ten feet at the 12th, almost holed out at the next and put his tee shot to ten feet on the 14th to join the lead.
English put an approach to six feet at the 13th to edge back ahead but DeChambeau missed a nine footer for eagle on the 16th and Ancer birdied the same hole as he got up and down from the sand to get it back to a three way tie.
18 holes to play @WGCFedex 📊#WGCFedex
— The European Tour (@EuropeanTour) August 7, 2021
The long time leader also recovered from the sand on the 16th to get himself back in front on his own and a wonderful approach to eight feet at the 17th meant he was two ahead.
Ancer bogeyed the 17th and 18th to slip out of a share of second where he was replaced by Smith.
The 27-year-old made a slow start as he sandwiched birdies on the second and third with bogeys on the first and seventh before a 23 footer on the ninth helped him turn in red numbers.
He then holed from 11 feet at the 12th, hit a stunning tee shot into the 14th, got up and down on the 16th and hit a wonderful second to five feet at the last.
Poulter birdied two of his last three holes in a 67, a score matched by Scheffler, while Zalatoris also carded a 67, Oosthuizen signed for a 68, and Johnson and Casey both recorded rounds of 65.
