UPDATE 1-Golf-Americans Stanley and Levin set Torrey Pines pace

* Stanley and Levin post 10-under-par 62s

* Perplexed Mickelson labours to a 77 (Updates at end of round)

By Mark Lamport-Stokes

SAN DIEGO, Jan 26 (Reuters) - Kyle Stanley was one of several players who took advantage of a picture postcard day on the California coastline, charging into a share of the lead in Thursday's first round at the Farmers Insurance Open.

With hardly a breath of wind at a sun-splashed Torrey Pines, the big-hitting American fired a sizzling 10-under-par 62 on the North Course, one of two layouts hosting the fourth PGA Tour event of the year.

Stanley, a PGA Tour rookie last year, recorded nine birdies, one bogey and an eagle at the par-five last to finish level with compatriot Spencer Levin, who also started out on the North layout.

Bill Haas, last year's FedExCup champion, opened with a 63 on the North while three-times winner and local fan favourite Phil Mickelson was left shaking his head after battling to a five-over 77 on the more difficult South Course.

"A round like today gives you confidence that you're doing the right things," Stanley told reporters after hitting an exquisite eight-iron from 173 yards to three feet to set up his eagle at the 18th.

"I know it was a 62, but it was a pretty boring round of golf. I hit a lot of greens and made a lot of putts.

"The course is in good shape, the fairways are nice and the greens are soft. You can be pretty aggressive with your irons but you've got to hit solid putts. If you don't hit solid putts, it (the ball) will bump up on you."

Haas, who has switched back to a belly putter for this week, was delighted with his form on the greens.

"It was a great start, mainly with the putter, and today it felt really good which is surprising because these greens are probably the toughest to putt on so far that we've played," he said.

TARGET SCORE

Asked if he had a specific score in mind at the start of the day and whether that was achieved, Haas replied: "I would say I surpassed that number.

"I just was hoping to play well and I knew on this course it's somewhat more gettable than the South. You can still shoot good scores over there too, but it definitely plays longer."

Mickelson, making his second appearance of the year on the PGA Tour, was dumb-founded by his struggles in the opening round as he mixed two birdies with seven bogeys.

"I don't know what happened, I just wasn't able to focus," said the American left-hander, who has not triumphed at Torrey Pines since 2001. "I made some bad swings just in the wrong spots and so forth.

"But I felt like my game was ready heading in, and I don't know what to say about the score because it was pathetic."

Three-times major winner Vijay Singh of Fiji opened with a 64 on the North Course and American world number nine Dustin Johnson, the highest-ranked player in the field, carded a 66, also on the North.

Johnson was especially pleased with his score after having to withdraw from last week's Humana Challenge at La Quinta, California due to a lower back injury.

"Last week was the first time I had walked in a few months but the knee's good," said Johnson, who had arthroscopic surgery on his right knee in November. "I feel great.

"I hit the ball well today, even though I missed a few fairways, but all the fairways I missed, it seemed like I was just a foot off. I hit my irons really good and I holed a couple of putts."

Defending champion Bubba Watson and fellow American Keegan Bradley, winner of last year's U.S. PGA Championship, returned 69s on the North layout while South African Ernie Els and Britain's Justin Rose launched their 2012 PGA Tour campaigns with 71s on the South.

The scoring average for the first round was 69.244 on the North Course and 72.846 on the South. (Reporting by Mark Lamport-Stokes in San Diego; Editing by Patrick Johnston; To query or comment on this story email sportsfeedback@thomsonreuters.com)