Austin Cook put himself in contention to defend his RSM Classic title with an impressive opening round at Sea Island as the three Irish players struggled to stay with the leading men.
The American, who saw off the challenge of JJ Spaun last year, carded a six-under par 66.
That left Cook two shots off the lead, which was held by Charles Howell III, alongside Spaun as the pair used their previous experience of this course to their advantage.
Australian Aaron Baddeley, Davis Love III and Chase Wright were all on five under while Graeme McDowell, third here in 2015, was two shots further back.
Seamus Power is two-under after a 70 while Padraig Harrington has a lot of work to do on three-over par after a disappointing day for him.
