Shane Lowry carded a six-under 65 to grab the solo lead after the first round of the RBC Heritage, while Dustin Johnson made a solid start on Thursday.
Lowry produced a bogey-free opening round in South Carolina, holing six birdies to take a one-stroke lead.
Five players, including Ryan Moore and Ryan Palmer, are one shot back at five under, while another eight are two shots adrift.
Billy Horschel and Patrick Cantlay are part of that group.
Johnson sits in a tie for 15th after opening with a three-under 68 that included four birdies and a bogey.
Matt Kuchar, the 2014 champion, and 2013 runner-up Webb Simpson are at two under.
Fresh off his collapse at the Masters, Francesco Molinari started the tournament with a three-over 74.
The Italian endured a rollercoaster round that included a double bogey and four bogeys.
Defending champion Satoshi Kodaira fared only slightly better, opening with a two-over 73.
A five-time runner-up at the tournament, Luke Donald carded a one-under 70 in the first round.