Stewart Cink shot an unblemished 64 to take a one-shot lead after the first day of the Farmers Insurance Open at Torrey Pines.
The 40-year-old is searching for his first win since he claimed the Open Championship at Turnberry in 2009 and got off to a solid start in California as he recorded eight birdies to top the leaderboard.
Gary Woodland was his nearest challenger as he fired five birdies and an eagle in a 65 as both men played the North Course on the first day.
The only man within four shots of the lead who had played the tougher South Course was another American in Pat Perez who fired a 67 which could hold him in good stead for the rest of the week.
Defending champion and world number one Tiger Woods was also playing the South Course and he had an unspectacular start as he registered a level-par 72.
Cink opened with a birdie at the first and picked up further shots on the third and fourth as he reached the turn in 33.
Further birdies followed at 11 and 13 before a run of three from the 15th to the 17th as Cink came home in five under.
"I've been playing fairly well this year," Cink said.
"I've been feeling confident, so I'm looking forward to the challenge (of the South Course). It's a good golf course to test yourself and see where you stand this time of year."
Woodland began his round on the back nine and picked up shots on the 14th and 17th before an eagle on the par-five 18th saw him go to four under.
Three further birdies moved him into second place alone, ahead of a group three players a shot further back made up of Australian duo Jason Day and Marc Leishman, South African Tyrone Van Aswegen and American Jim Herman.
Perez was sat in the group at five under after birdies on his first and seventh holes and a run of three more on his back nine gave him the lowest score of the day on the South Course.
DA Points and Bae Sang-moon were alongside Perez after firing 67s while David Lynn was the best of the Europeans a shot further back with birdies at two, four, nine and 18.
There was then a large group of players at three under including Phil Mickelson, Keegan Bradley and Scotsman Martin Laird.
Mickelson played one of the shots of the day after his second at the 18th left him by a fence near the car park but the Open champion chipped to within three feet and made an unlikely birdie.
Woods had no such luck as he endured an inconsistent day. The 14-time major winner birdied the second but then gave the shot back on five and it was similar story on the back nine as he bogeyed 11 before picking up a shot on 14.
"Even-par is not too bad," said Woods. "I didn't play the par-fives worth a damn today, that's paramount on the South Course.
"I didn't do that, so consequently, I didn't finish under-par."
Lee Westwood also struggled on the South Course as he fired a 73, while Ian Poulter had an even worse day as he shot a three-over par 75.