Ireland's Shane Lowry carded a bogey-free round of 65 to take a one-stroke lead after the first round of the RBC Heritage tournament in South Carolina.
Playing with a driver he used for the first time when he missed the cut at the Masters last week, the Offaly man carded birdies on all three par-fives to take a slender advantage.
Behind Lowry, four Americans - Trey Mullinax, Daniel Berger, Luke List and Ryan Moore - all carded five-under-par scores of 66.
Seamus Power, carded a three-under 68 alongside Graeme McDowell, with Luke Donald and Ian Poulter among those two strokes further back.
Afterwards Lowry revealed the extent of the problems he has been having since starting the European season off on a high note with victory in Abu Dhabi.
He told a post-round press conference: "Pretty much my whole game felt good - I haven't had that feeling in a while.
"I just played them nicely today. I've struggled off the tee quite a bit this year and I managed to find a new driver that I like. I hit that pretty good."
Lowry had been struggling to break 70 all season and back-to-back rounds of 78 and 73 saw him miss the cut at Augusta.
He said he had tried at least 30 different drivers before finding the one which could help him reverse his recent fortunes.
"We've done a lot of work and I managed to find one I like," he added. "Today was the first day that I hit the ball well off the tee.
"I'm happy with my golf. My scores haven't been great of late, but I felt like I've been playing okay. So maybe this is a reward for the perseverance."