Webb Simpson fired another six-under 65 to lead the RBC Heritage, while Brooks Koepka continued his strong start on Friday.
Simpson, the 2013 runner-up at the PGA Tour event, managed nine birdies and three bogeys, shooting a second straight 65 to get to 12 under.
The American holds a one-stroke lead over Bryson DeChambeau (64) and Corey Conners (63) after the second round, which was suspended for two hours due to dangerous weather.
Conners' bogey-free 63 was the equal best second round, alongside Jhonattan Vegas and Tyler Duncan.
DeChambeau, meanwhile, produced a stunning finish to his round, making six birdies on his final nine holes.
Ryan Palmer (67) and Matt Fitzpatrick (66) are at 10 under, sharing fourth spot on the leaderboard.
Koepka followed up his opening-round 67 with a 66 to be at nine under and in a tie for sixth alongside Abraham Ancer (64), Vegas, Matthew NeSmith (67) and Ian Poulter (69).
Dustin Johnson managed a five-under 66 to be at eight under, two shots better off than Jordan Spieth (70).
World number one Rory McIlroy got going with a six-under 65 that saw the Northern Irishman climb into a tie for 45th at five under.
Rickie Fowler and Jason Day were among the players to miss the cut on a day which saw Nick Watney withdraw after testing positive for coronavirus.