World number one Jason Day returned to the top of the leaderboard following his Masters disappointment as he took a share of the lead at the RBC Heritage.
The Australian, who had won his last two tournaments before failing to mount a serious challenge at Augusta, shot 69 to join American duo Kevin Chappell and Charley Hoffman on six under after two rounds.
Overnight leader Luke Donald is a shot back after following his five-under opening round with a 71, while Scotland's Russell Knox joins him in a tie for fourth after shooting a 65, the best round of the week so far.
Day is looking for his third PGA Tour title of the season, after wins in the Arnold Palmer Invitational and the WGC-Dell Match Play in March.
Starting on the back nine, Day dropped a shot on the 17th before immediately recovering the shot with a birdie. He picked up further shots on the second, third and sixth but bogeyed the par-five fifth.
Englishman Donald, who has three second-placed finishes at the Harbour Town Golf Links, had shared the lead with Branden Grace overnight after six birdies on Thursday, but his second round contained just the two birdies, which were cancelled out by a double bogey on 14.
Knox, who won the WGC-HSBC Champions in November, had eight birdies and two bogeys as he joined Donald on five under for the tournament.
English duo Paul Casey and Matt Fitzpatrick missed the cut on three over, with Northern Ireland's Graeme McDowell finishing two shots worse off.
American Bryson DeChambeau, in his first tournament as a professional, is three under par after a 69 which contained six birdies, two bogeys and a double on the eighth while South African Grace slipped from tied first to tied 21st after a three-over 74.