Englishman Danny Willett, Australian Adam Scott and Americans Jason Dufner and Charley Hoffman opened with 68s in the first of the year's four elite World Golf Championships events while world number one Jordan Spieth carded a 69.
"It's very demanding off the tee, there's trouble on every single hole, so you have to stand up and really commit to a shot," Spieth told Golf Channel after carding five birdies and two bogeys.
"And it's not done from there. A lot of times we play courses where there is a miss (for the green) where you can still make par but on quite a few holes out here you just can't miss it.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"I'm very pleased to get in under par on this golf course. This course normally gets my number but I beat it today."
American Spieth attracted the biggest galleries of the day in a high-profile grouping with second-ranked Australian Jason Day and third-ranked Northern Irishman Rory McIlroy.
Day offset four birdies with four bogeys to return a 72 while McIlroy spoilt an encouraging start week when he double-bogeyed his final hole, the par-three ninth, to shoot a 71.
"I was leaving a lot of putts short. But I guess to be expected," said four-times major winner McIlroy, who this week switched to an unconventional cross-handed putting grip.
"It's the first day competitively with a bit of a new grip with the putting. Disappointed with the finish, just get out there tomorrow, try to pick up those shots quickly again and start from there."
Piercy, a three-times winner on the PGA Tour, twice got to seven under but twice slipped back as he recorded two bogeys in five holes over the tough closing stretch.
"The last five holes, I was a little off," said the 37-year-old American. "I had the wind off my left which sometimes isn't my favourite and just hit a couple of weird shots."
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)
