Harris English held a two-shot lead at the halfway stage of the FedEx St Jude Classic after a second-round 64 sent him to 10 under-par in Memphis.
Shawn Stefani was second after a 65 saw him move to eight under overall, three shots ahead of Paul Haley II and Scott Stallings.
Padraig Harrington is well down the field on one under.
"I'm really trying to birdie every hole" - Harris English
English's 66 on day one had put him in a six-way tie for the lead after the first round.
However, while many around him could not match their first-round exertions, the American exceeded his efforts - although it could have been better considering he dropped a shot at the final hole.
He made a superb start today with three birdies and an eagle in his first five holes, the latter coming on the par-four fifth when he holed out from 175 yards.
Further consecutive birdies at the 15th and 16th were followed by a bogey at the last as he finished with a six-under-par 64.
The 23-year-old is in only his second year on the PGA tour and he told the official website: "I'm still getting comfortable out here, just trying to get in the hunt of a golf tournament every time."
He added: "When I get in that kind of situation, everything is pretty much going my way and I'm very much in control of my ball.
"I'm really trying to birdie every hole."
Stefani was almost as impressive as he followed yesterday's 67 with a 65, including five birdies and no bogeys to move two shots behind English.
Three shots further adrift were Haley and Stallings.
The former added a 68, including three birdies and one bogey, to his first-round 67 as did Stallings although it could have been so much better given his poor start which saw him sink a double bogey on the 11th hole after beginning his round on the back nine.
There were two further bogeys although the damage was offset by six birdies.
Davis Love III had been in the group of six at the top of the leaderboard overnight.
However, after starting on the back nine, the American dropped a shot at the 11th and although he picked up two birdies, he hit a double bogey at the par-four 17th.
The front nine included a birdie and a bogey before he picked up a valuable shot at the final hole to card a round of 70, four under overall.
Similarly, Glen Day, whose 66 yesterday was followed by a 70 comprising four birdies and four bogeys.
Justin Hicks followed up yesterday's 67 with a 69 while Doug LaBelle hit four birdies en route to a 66 and Nicholas Thompson hit a 69 to complete the group on four under.
Ian Poulter was the leading European on three under but it could have been better without a disappointing back nine.
The Englishman was well in contention and going well with five birdies in the first 10 holes.
However, three bogeys scuppered his round and he carded a 68 to find himself in a 12-way tie for 10th which also included the likes of defending champion Dustin Johnson.