Haas, seeking a third career victory go with two titles he won last year, had eight birdies in his six-under 66 that gave him an 11-under total of 133 heading into the weekend at Torrey Pines.
Haas, who lost in a playoff at the Bob Hope Classic last Sunday, was two strokes in front of Anthony Kim, who carded a 67 for 135.
Woods, whose seven professional victories at Torrey Pines include six titles in this US PGA tour event as well as a 2008 US Open triumph, carded his second straight 69 to lie five off the lead on 138.
The former world number one, hoping 2011 will be a season of renewal after his turbulent 2010, strung together four birdies in a row from the third hole, then found himself battling to hold his round together.
“I got off to a good start today,” said Woods, who didn’t win a title in 2010 as he was engulfed in a sex scandal that ultimately ended his marriage. “I was making some putts, hitting some good shots.
“I lost it in the middle part of the round, and then I got it kind of got it back in the end.
“You know, it’s a round that could easily have slipped away, but I got it back at 16 and 18.
Woods bogeyed three holes on the back nine from bunkers. At two of them - the par-three 11th and the par-four 14th - he needed two shots to get out of a bunker.
Woods salvaged his day with his final three holes. He birdied the par-three 16th, where he fired at the pin and made a 12-footer, then saved par with a 20-foot putt at 17.
At the par-five finishing hole he reached the green in two en route to a closing birdie.
Woods said 18 showcased “probably my two best shots all day.”
“Just a bomb down there, and I hit just an up in the air five-wood, a little slight draw into the wind to hold it,” he said.
“It’s nice when I’m able to pull off shots like that because I know it’s in there - it’s just a matter of doing it,” added Woods, who is still waiting for the swing changes implemented with coach Sean Foley last year to pay dividends.
A group of seven players sharing third on 136 included Masters champion Phil Mickelson, a three time winner here, defending champion Ben Crane and John Daly, who hasn’t won since a victory here in 2004.
Mickelson and Daly both shot 69s while Crane climbed up the leaderboard with a 66 - all on the toughened-up North Course.
After several missed chances, Mickelson birdied his last two holes to keep himself in position to strike.
“It’s a good way to finish the round, to make those two birdies and turn the round that wasn’t going the way I wanted into an OK round,” Mickelson said. “I’m looking forward to the weekend.”
They were joined by Sweden’s Fredrik Jacobson (69), Bubba Watson (65), Rickie Fowler (71) and Hunter Mahan (67).
Haas got off to an inauspicious start when he bogeyed his second hole of the day - the 11th.
But he birdied three in a row from the 12th, and put together four birdies in a row from the 18th. He added one last birdie at the par-five sixth that moved him to 12-under for the tournament, but gave that back with a bogey at the par-three eighth.
“A nice 36 (holes) on the weekend could turn this into a great week,” Haas said.
Kim’s round also left him looking forward to the weekend.
Playing alongside Woods, Kim birdied the first four holes, reached nine-under at the turn and seized a share of the lead on 10-under through 10.
He bogeyed 11 before closing with seven pars.
“I’m really close,” Kim said. “I know I’ve said it a million times. I’m not going to say it again. I’ve just got to make a couple of birdies and see what happens.”
Surprise first-round leader Kang Sung-hoon of South Korea slid down the leaderboard, following up his opening 64 with a 76 for four-under 140, still making the halfway cut that fell at one-under with room to spare.
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