Bill Haas positioned himself for a run at a Riviera repeat on Saturday, firing a superb seven-under par 64 to seize a three-stroke lead after the third round at the US PGA Tour Northern Trust Open.
Haas, vying to become the first player since Phil Mickelson in 2008 and 2009 to post back-to-back victories at Riviera Country Club, started the day four shots off the lead.
But he avoided any bogeys on the classic par-71 course despite the challenging firm conditions produced by warm, sunny California weather.
Haas's seven-under effort beat the next-best round of the day by three strokes and gave him a 54-hole total of 12-under 201.
Reigning US Open champion Webb Simpson and 2011 Masters winner Charl Schwartzel both shot 68 to share third on nine-under par 204 along with John Merrick, who was in sole possession of second place before a bogey at the last to complete a one-under 70.
"Bill shooting seven-under is incredible out there," Simpson said. "I felt like my three-under was pretty good."
World number three Luke Donald of England (70) and overnight co-leader Fredrik Jacobson of Sweden (72) were a stroke back on 205.
Haas had five birdies and a chip-in for eagle on the par-four 10th hole -- the same hole where he rolled in a 45-foot birdie putt to beat Mickelson and Keegan Bradley at the second hole of sudden death last year.
That victory remains the most recent of four US PGA titles for Haas, who won the Tour Championship in 2011 to take the US circuit's $10 million playoff crown.
"It's very difficult in this game to just pull away from the rest of the field," Haas said of the task facing him on Sunday. "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 try to stay in the moment, don't let my emotions get the best of me. ... The guys behind me are going to make birdies and it will certainly get closer at the top. So I've just got to try to hang in there and give myself a chance on the back nine."
After birdies at five and seven, Haas's birdie at the ninth ignited a birdie-eagle-birdie stretch that cemented his spot atop the leaderboard.
"Ten, I hit a nice three-wood there and kind of had a tricky angle. I had a really nice lie and in that grass you can really spin one and it came off just like I wanted," he said of the eagle that gave him a two-shot lead.
Haas picked up another stroke at the par-five 17th, where he narrowly missed holing out for eagle from a greenside bunker and tapped in for birdie.
Simpson, who had four birdies and a bogey, said the firmness of the course reminded him of the notoriously tough conditions of a US Open.
"It was difficult to get the ball close to the pin," he said.
Overnight co-leader Sang-moon Bae of South Korea showed just how badly things could go wrong.
He opened with the first of two birdies, but finished with a five-over 76 that included five bogeys and a double-bogey seven at the 17th to drop into a tie for 13th.
Given the difficulty of the conditions, Schwartzel said he wouldn't be changing anything in a bid to make a final-round run at Haas.
"It was a lot harder than the other days," said the South African, who was runner-up at the European Tour's Joburg Open last Sunday.
"It's easy to make bogeys," Schwartzel said. "I probably won't change anything, just keep playing the way I am and see if I can give myself chances."