Harris English carded a second round 65 to take a two shot lead into the weekend at the 2021 WGC-FedEx St Jude Invitational but had an impressive pack chasing him down at TPC Southwind.
The American followed up an opening 62 to get to 13 under but Mexican Abraham Ancer and Australia's Cameron Smith both matched his first round effort to be the closest challengers, with Smith remarkably recording just 18 putts in round two.
Ian Poulter - a two time World Golf Championships winner - was then at ten under alongside Americans Sam Burns and Scottie Scheffler, a shot clear of Major Champions Bryson DeChambeau and Louis Oosthuizen.
World Number 14 English is searching for a first WGC win in Memphis but claimed victory at this event eight years ago and has two wins on the US PGA Tour in 2021.
"I've been playing really solid," he said. "When I miss the greens, I feel like my short game's been on point and I feel like I'm putting it well. Made some good saves for par, good birdie putts.
"Everything is clicking right now so I feel like my strategy has been working off the tee - a lot of right to left holes on the three wood, left to right holes I feel I can hit my fade with the driver and it's been working out."
Starting on the tenth, English holed a 35 footer on the 11th, put his tee shot to ten feet at the par three 14th and played a lovely chip to set up a birdie on the par five 16th.
He dropped a shot on the second but hit back in spectacular style on the par five next, putting his second to five feet and rolling in the eagle.
A tee shot to nine feet on the eighth then gave him a fourth birdie of the day and a three shot lead in the clubhouse.
Smith then cut it to two with his remarkable display that matched the lowest round of the week.
Everything is clicking right now so I feel like my strategy has been working off the tee
He birdied from five feet at the first and holed a bunker shot for an eagle at the third before a 30 footer at the fifth followed by a six foot putt at the next saw him turn having taken just seven putts - holing from off the green in pars at the fourth and eighth.
He made lengthy putts at the 12th and 14th and took advantage of the 16th from the fringe before a two putt on the 18th - just his fourth of the day - denied him the accolade of having had less putts than holes played.
Ancer holed a pair of 16 footers on the 11th and 12th before he hit a smart approach into the 15th and made the most of the next as he got up and down from the sand.
A hat-trick of birdies from the first then catapulted the 30-year-old up the leaderboard and he holed a 15 footer on the seventh to get alongside Smith.
Poulter recovered from a poor tee shot on the third by putting his third shot to 15 feet and making the birdie, before some wonderful iron play brought gains from inside ten feet at the fourth and sixth.
The Englishman got an unfortunate bounce off a tree at the ninth and had to go back to the tee and, despite hitting the same tree again, he found the green with his fourth and holed a 35 footer to keep the damage to one with a first bogey of the week.
A birdie from 13 feet at the 12th recovered that shot before he got up and down on the 16th for a 66 after being prevented from putting by the collar.
Burns was bogey free in his round of 64, while Scheffler made six birdies and a bogey in a 65.
Oosthuizen is third in the Race to Dubai Rankings in Partnership with Rolex after three top threes in Majors his last four starts and the South African was bogey free in a 64.
American DeChambeau made six birdies and two bogeys in a 66 to sit a shot ahead of countrymen Jim Herman and Will Zalatoris.
