First-round leader Seamus Power of Ireland followed up an opening 65 with a 69, leaving him four shots off the lead at the FedEx St Jude Classic.
Power had lead at five under after round one but, with a late tee-time on Friday, he was quickly overtaken by the early starters with world number two Dustin Johnson blasting his way to the top of the leaderboard at 10 under courtesy of a 63 which included seven birdies and an eagle.
However, Power was not letting the gap get to him as he moved to seven under par for the tournament after his first six holes.
Starting at the 10th he put together a run of three consecutive birdies at the 11th, 12th and 13th before dropping a shot at the 15th. A double bogey on the par-4 ninth however left him six under par overall.
The Waterford man is badly in need of a good week as he currently sits 129th in the FedEx Cup standing and outside the top-125 who maintain their playing privileges for next season.
Pádraig Harrington, despite a double bogey on the 18th and a round of 72, squeezed inside the cut.
Shane Lowry, who secured a US Open spot via qualifying on Monday, also survived the cut with three birdies on his final nine holes for a round of 67 leaving him one under par overall. One shot better off than Harrington and the weekend cut.
Winning the tournament would take Johnson back ahead of Justin Thomas as world number one going into the US Open and his efforts on Friday earned him a one-shot lead over fellow Americans Ryan Blaum and Andrew Putnam.
Blaum redeemed a bogey at the first with seven birdies in a 64 and Putnam matched that effort as both seek a first win on the PGA Tour.
Two-time Ryder Cup player Brandt Snedeker was three off the lead at seven under, one ahead of Chez Reavie with Brooks Koepka a further shot back.
Five-time major winner Phil Mickelson was four under after two birdies in his last three holes.
