LOS ANGELES, Feb 14, 2013 (AFP) - Kuchar's seven birdies on the par-71 Riviera Country Club lay-out included three to open his round.
"I got off to a great start," the four-time winner on the US PGA Tour said. "Birdied my first three and all were kick-in birdies -- I think all within probably four feet."
Garcia, runner-up at the European Tour's Qatar Masters last month, teed off on 10 and also opened with three birdies. His lone bogey of the day came at the 13th, and he picked up four more birdies on his inward run -- capping his 65 with a birdie at the ninth as fog from the Pacific Ocean drifted across the course that had been bathed in sunshine all day.
Journeyman Brandt Jobe -- playing in the first group off the first tee -- had set an early target with a five-under 66 that left him in third when darkness halted play with 18 players yet to complete their rounds.
Charlie Beljan was at five-under through 17 and opted to complete the 18th when play was called. He bogeyed to end up in a group with England's David Lynn and Korean-American rookie James Hahn on 67.
A group of 11 players were a further shot back on 68, including England's Lee Westwood, US veteran Fred Couples and South Korean Sang-moon Bae.
Kuchar said some work this week with his coach had him feeling good about his game and eager to play after a three-week break that included a family holiday in Hawaii.
The vacation came after a solid start to his season. He tied for ninth at the season-opening Tournament of Champions and shared fifth at the Sony Open before a top 20 finish at the Humana Challenge in the California desert.
Kuchar said he was glad to have some rounds behind him at this point in the year, while a handful of notable players -- including world number three Luke Donald, Northern Ireland's Graeme McDowell and Australian Adam Scott -- were launching their seasons at Riviera.
"It's always interesting to see guys figure their schedule out," Kuchar said. "I had three really nice weeks, almost three top-10s, then went to Hawaii for about eight days, had a blast. I came back refreshed and energized and ready to get back playing again."
Garcia was delighted to get his afternoon round off to a quick start.
"First tournament in the US this year, it was nice to start like that with three nice birdies. I managed to play quite good -- not extremely well.
"I was more comfortable with my irons than my driver," Garcia said.
A chip from just behind the green left him a two-footer for birdie at 10. He was on the green in two at the par-five 11th, but at 12 he pulled his drive, but recovered with a seven-iron to 15 feet and made that.
Garcia said the change in conditions as he finished his round was dramatic, with his group unable to see where their tee shots landed on nine because of fog.
That didn't prevent him from making the birdie that gave him sole possession of second place.
Most of the afternoon starters found scoring tougher. Donald finished the day with a two-under 69 but playing partners Scott and McDowell couldn't break par, Scott finishing on even par and McDowell two-over on 73.
Leading first-round scores on Thursday in the $6.6 million US PGA Tour Northern Trust Open (Darkness halted play with 18 players on course. USA unless noted, par-71):
64 - Matt Kuchar
65 - Sergio Garcia (ESP)
66 - Brandt Jobe
67 - David Lynn (ENG), James Hahn, Charlie Beljan
68 - Pat Perez, Jim Furyk, Lee Westwood (ENG), Fred Couples, Fredrik Jacobson (SWE), Tim Herron, Robert Streb, John Merrick, Sang-moon Bae (KOR), Bob Estes, Ben Curtis
69 - John Rollins, Michael Block, Greg Chalmers (AUS), Greg Owen (ENG), Luke Donald (ENG), Charl Schwartzel (RSA), Peter Hanson (SWE), Marc Leishman (AUS), Angel Cabrera (ARG)