Los Angeles - Shane Lowry is hoping to learn from past experience to maintain his one-shot lead at the RBC Heritage after opening with a bogey-free 65 on Thursday.
In the Irishman's only other appearance at the PGA Tour event two years ago, he shot a 65 in the first round before dropping a 75 in the second and finishing with a two under total at the end of Sunday's round.
"A couple of years ago I got off to a good start and I maybe tried to force it a little bit," Lowry said.
"So just try to stay patient the next few days.
"I enjoyed today. It's nice to shoot a good score. And it's my first good score in a few weeks. So just enjoy that and just get out there tomorrow and get after it."
Lowry has a slight lead over five Americans, including Ryan Moore and Luke List, who all shot five under 66 at the Harbour Town course in Hilton Head, South Carolina.
Kevin Na, Rory Sabbatini and Patrick Cantlay are part of a group of eight players tied for seventh after shooting 67s. Lowry has his work cut out for him on Friday as there are two dozen golfers within three shots of the lead.
"I'm happy with my golf," Lowry said.
"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."
Lowry needed just 27 putts in the first round, but more importantly, he stepped up his game by making birdie on the par-fives.
On each of the three pars fives he sank birdie putts of three feet or less.
"It was something I've been struggling with - my par-five scoring hasn't been very good," Lowry said.
"I just played them nicely today. I 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. And when you do that on par-fives it always gives yourself a chance."
Leading first round scores from the PGA Tour's RBC Heritage on Thursday (Par 72, USA unless stated):
65 - Shane Lowry (IRL)
66 - Trey Mullinax, Daniel Berger, Luke List, Ryan Moore, Ryan Palmer
67 - Rory Sabbatini (SVK), Alexander Norn (SWE), Sam Burns, Peter Malnati, Scott Piercy, Kevin Na, Billy Horschel, Patrick Cantlay
68 - Emiliano Grillo (ARG), Rafael Cabrera (ESP), Seamus Power (IRL), Hudson Swafford, Charley Hoffman, Chez Reavie, Dustin Johnson, Brian Stuard, Jonathan Byrd, Michael Thompson, Scott Langley, Graeme McDowell (NIR)