LOS ANGELES — Bill Haas had no reason to think this round at Riviera was going to be anything special.
With an iron in his hand, he failed to make birdie on the par-5 opening hole, the easiest on the course. Solid iron shots led to a pair of birdies on the front nine, and with Riviera playing tough in warm, dry conditions Saturday, he was part of a large group challenging for the lead.
Three holes changed everything.
Haas made a tough 30-footer for birdie on No. 9. He pitched in from 60 feet for eagle on the scary par-4 10th. And he hit a good bunker shot with little margin for error on the par-5 11th that set up a birdie.
Just like that, he was on his way to 7-under 64 and a three-shot lead going into the final round of the Northern Trust Open.
His 64 was the best round of a difficult day by three shots in the PGA Tour event, and it was nearly eight shots better than the average score. It put Haas at 12-under 201.
"It's very difficult in this game to just pull away from the rest of the field," Haas said. "You've only seen a few guys ever really do that, and those are guys like Jack Nicklaus, Tiger Woods, Phil Mickelson. So I think I've just got to stay in the moment, don't let my emotions get the best of me."
John Merrick bogeyed the 18th hole for 70 and joined Webb Simpson (68) and Charl Schwartzel (68) at 9-under 204.
Luke Donald overcame three bogeys in a six-hole stretch with four birdies on the back nine to salvage a 70 that put him four shots behind, along with second-round co-leader Fredrik Jacobson (72).
Second-round co-leader Sang-Moon Bae shot 76 to fall to 4 under.
Mickelson had hoped to make a move and instead went the other direction. He missed three par putts of about 6 feet on the front nine and had 72, which put him nine shots behind.
LPGA: Jiyai Shin and 15-year-old amateur Lydia Ko shot 3-under 70 to tie for the lead after three rounds of the Women's Australian Open, six shots ahead of Beatriz Recari (71) at 17-under 202. Seminole's Brittany Lincicome (72) was at 6 under in the season-opening tournament in Canberra, and Tampa's Cindy LaCrosse (74) was at 3 under.
Champions: Bernhard Langer shot 2-under 70 to take a three-shot lead at 12-under 132 after the second round of the ACE Group Classic at Naples. Chien Soon Lu (68) and Tom Pernice Jr. (69) were tied for second.