Matt Kuchar shot a bogey-free morning round of seven-under 64 to seize the early lead at the Northern Trust Open.
Kuchar birdied his first three holes at Riviera on his way to a front-nine 31. He finished with seven birdies.
"I got off to a hot start today and was playing solid golf," he said.
Kuchar holds a two-shot lead over Brandt Jobe, who shot two-under 69.
Things didn't go as well for the morning marquee threesome of Phil Mickelson, Bill Haas and Keegan Bradley, who shot a collective one-under par. Haas, the defending champion, shot one-under 70 while Mickelson and Bradley both finished at par.
Last year, the trio was a total of 21-under par and ended up in a playoff won by Haas.
"Had to fight to make pars and pretty fortunate to shoot even par," Mickelson said after his round.
Mickelson's group is set to return Friday with a 12:01 p.m. tee time on the first hole.
Thursday was a good day for 53-year old Fred Couples, who shot three-under 68.
"I can figure my way around this course," said Couples, a two-time Northern Trust Open winner.
Couple's playing partner, Lee Westwood, also shot three-under. Bubba Watson, the reigning Masters champion and third man in the grouping, lagged well behind at six-over 77. He is currently tied for 119th in the 144-player field.