South Africans Branden Grace and Tyrone van Aswegen will be around on the weekend but Ernie Els missed the cut on Friday.
Grace is the defending champion is T32 after a level par 71 in the second round. He had an otherwise flawless round but a double bogey on the par 5 fifth severely hampered his progress.
He made just two birdies – on 2 and 15 – to go with 15 pars in South Carolina.
Grace is seven shots adrift but not completely out of it as he knows how to go low on this course.
Compatriot Van Aswegen fired a second round 70 for a tournament total of -2 at the halfway mark. He copied Grace with only two birdies, one mistake – a bogey on 3 – to go with a host of pars.
The Big Easy joined the likes of Matt Fitzpatrick, Charley Hoffman and Danny Willet with the weekend off.
Els needed a birdie on the last and some favours from the field to sneak into the weekend but three putted albeit from long range.
A front nine 39 did the damage for the smooth-striking South African, who closed with level par 35 including his dropped shot at the last.
Co-leader Graham DeLaet always loved playing at Harbour Town Golf Links, but rarely got the results he thought he should – until this week.
DeLaet followed up his career-best 6-under 65 in the first round with a 67 on Friday to share the lead with Luke Donald midway through the RBC Heritage.
Donald also shot 67 to reach 10-under 132, two in front of Ian Poulter and Webb Simpson.
Poulter and Simpson each shot 68.
