Ireland's Seamus Power carded a three-under 69 to close out the opening round of The Genesis Invitational one shot behind leader Denny McCarthy.
Power began with a par and a bogey on his first two holes but picked up four shots from there to head to the clubhouse, tied with American Patrick Rodgers on three under par.
The duo trail McCarthy by one at the top of the leaderboard after the American nabbed the outright lead with a clutch eagle on the par-five 18th.
World number one Scottie Scheffler split four birdies with two bogeys to sit tied for fourth on two under.
"It's been a long time obviously since I played a lot of golf in Ireland," Power said. "But mentality becomes the biggest thing.
"It's pretty easy to get down and to get a bit like mad at everything, the conditions and everything is harder today. It's just to kind of somehow keep your head in it and stay positive somehow and just get through it."
Power is hunting for his third PGA Tour title and sits alongside Patrick Rodgers who also signed for a round of 69.
Rory McIlroy had an up-and-down opening round as he finished the day even par.
Starting on the back nine, he offset an early bogey with a birdie at the turn, but another bogey on the first threatened to derail his day.
However, McIlroy maintained his composure and salvaged another birdie on the eighth hole to keep himself in the hunt.
Shane Lowry is also still in contention on a day when uncharacteristic wet and windy conditions in San Diego kept scores down. Only 19 of the 72 players in the field shot even par or better.
Lowry Irishman is tied for 20th after his round of 73 left him on +1.
There will be no 36-hole cut as all players in the field will play all four rounds.
