Three of the world's top players sit at the top of the Northern Trust leaderboard at the halfway mark.
World number one Dustin Johnson, three-time major winner Jordan Spieth and Rickie Fowler all sit on six under along with Venezuelan Jhonattan Vegas.
Spieth was in imperious form, shooting through the pack with a five-under-par 65, which contained seven birdies, including five in a row on the back nine.
Vegas also shot a blemish-free 65 to move up 19 places, while Fowler carded a 66 and Johnson, who was one shot off the overnight lead, went round in 69.
Matt Kuchar, runner-up at the Open, shot the round of the day with a seven-under-par 64, made all the better by the fact he was two over for his round after seven holes.
The American fired six birdies on the back nine to get to five under overall.
Bubba Watson is also on five under while England's Justin Rose, Spaniard Jon Rahm and first-round leader Russell Henley are all on four under.
It was a better day for Rory McIlroy, who opened with a three-over-par 73 on Thursday. The Northern Irishman sank three birdies and a bogey in his 68, which saw him make the cut by a single shot on one over.