Shane Lowry was "chuffed" to find his driving mojo and race into the clubhouse lead with a bogey-free 65 in the RBC Heritage at Harbour Town.

The world number 50 has struggled to find a driver since breaking his favourite club before his win in Abu Dhabi in January.

But after putting a new one in the bag for the Masters, where he failed to make the cut, he missed just one fairway and made six birdies to lead by a shot in the clubhouse from Trey Mullinax and Daniel Berger with 2013 winner Graeme McDowell tied sixth after a three-under 68 in Hilton Head.

"I just tried to go out there and just not make too many mistakes. And when I made a mistake, I managed to get up and down," said Lowry, who scrambled immaculately and putted well with a new putter in his bag.

"I hit the ball pretty well off the tee, which gave me a lot of chances. And I knew when I saw the tee times it was a decent draw to get out there first thing and it wasn't very windy.

"When it gets windy around here it can swirl in the trees and get very difficult. It wasn't too bad this morning. But, yeah, I'm chuffed because my golf has not been great as of late. It's a funny game. You never know what's around the corner."

Starting on the back nine, Lowry got off to a flying start when he made a 20 footer at the 11th, and an eight-footer at the 12th to move swiftly to two-under, then hit a wedge close at the par-five 15th and made the putt to get to three-under.

He would go on to birdie the two par-fives on his back nine, two-putting the second before getting up and down from sand at the fifth.

"Something I've been struggling with, my par five scoring hasn't been very good, and I just played them nicely today," said Lowry, who rounded off a positive day by holing an eight-footer for a closing birdie..

"I think I struggled off the tee quite a bit this year, and I managed to find a new driver that I like. So I hit that pretty good. And when you do that on par-fives, it always gives you a chance."

Lowry's goal now is to remain patient with wind and tough conditions forecast for Friday.

He opened with a 66 on his debut two years ago but slipped back into the pack as the week wore on and he knows what he has to do to contend.

"I felt like the course was easy, gettable for me today,” he said. “But it's a tough golf course. It doesn't take a whole lot to win around here. Score-wise, something in the low teens will definitely come close. You're going to make a few bogeys as the week goes on. But you just need to be patient."

Lowry is keen to recapture the form that ebbed away after his win in the Abu Dhabi HSBC Championship in his first start of the year, and he believes today's round was a reward for his patience as he finished the day with +6.136 strokes gained from tee to green.

"My game felt good out there,” he said. “I hit the ball well off the tee. And then I hit my irons decently, when I missed a green, it was in the right spots, and I managed to get them up and down. I'm happy with my golf. My scores haven't been great as of late. But I felt like I've been playing okay. So maybe this is a reward for the perseverance.

"When you hit the ball well off the tee, it gives you chances and gives you chances to shoot a good score. The fairways are quite narrow, the greens are quite small. You can feel the wind getting up, but we didn't have too much of it this morning, which was nice.

"I got off to a nice start, I birdied two of the first three. To be honest, I felt like I missed a couple of chances in the middle of the round. But I just stayed patient, kept going.

"And I knew that if I hit good tee shots, my iron play felt good, and I felt like I could make birdies. It was nice to have that feeling out there.

"Pretty much my whole game felt good. I put a new putter in the bag this week. And I have a new driver for the last couple of weeks. I've been struggling with driver off the tee. So everything felt good. I haven't had that feeling in a while.

"It's a great week.... such a chill atmosphere. And especially the week after Augusta, which is probably the most stressful week of the year."

Driving the ball well is critical for Lowry, and he is keeping his fingers crossed that he has On his struggle to find a driver he likes, he's hoping the quest is finally over.

"I've tried so many drivers this year, all the companies, and I finally got one I like from Srixon," he explained. "They sponsor me. And they've been great. We've done a lot of work, and I managed to find one I like and feel like I can trust it there.

"So hopefully it keeps going. Today was the first day that I hit the ball well off the tee. It felt okay last week in Augusta, but today was the first real day."

McDowell was also pleased to break 70 at a venue he likes, following a bogey at his opening hole with four birdies, including a bonus birdie from just off the green at the eighth, his 17th.

"This golf course gets you defensive, especially off the tee," said McDowell, who returned the winner's enclosure for the first time in more than three years in the Dominican Republic three weeks ago.

"You don't get on many tee boxes here and feel like you can open the shoulders and give it a rip.

"I felt a little steer-y out there. My iron playing was a little off. There's lots of room for improvement. But scoring-wise, it felt good. And the greens kept the ball reasonably under control.

"On the tee, I did what you have to do today, give yourself a few looks at the greens and make a few putts. But blustery enough out there and that kept us on our toes."

While he's bracing himself for tough conditions on Friday, he's finally playing with freedom again after that recent win and looking to push on.

"It's lifted a huge weight off my shoulders," McDowell said. "I've been kind of half my mental self the last two years. I think that's probably a fair description because I haven't allowed myself the opportunity to go and play free golf. I needed it way too much.

"And I've needed the simple things. I needed a playing status for the PGA Tour. It's not something I'm used to trying to fight for. And it's different. It hurts you on a Saturday, Sunday, especially, because you don't have that freedom of, okay, now we've made the weekend, let's put the accelerator down, and go see what we can do.

"It's more like, man, I need a 15th here; man, I need an 8th here. It's been a bit small-minded, I suppose and, as I say, it's affected me mentally and led to some frustrating golf the last few years."

Seamus Power, who was one of the afternoon starters, was two-under through seven holes on his debut at Harbour Town.