Defending champion Bill Haas fired a 7-under 64 on Saturday to grab a 3-stroke lead after three rounds of the Northern Trust Open.
Haas turned in the low round of the day and jumped into the top spot at 12- under 201 through 54 holes. On Sunday, he'll shoot for his first PGA Tour win since dispatching Phil Mickelson and Keegan Bradley in a playoff here last year.
A pair of major winners, Webb Simpson and Charl Schwartzel, both shot 68s at Riviera Country Club to move into a tie for second place with John Merrick (70) at 9-under. The 2011 Masters champion Schwartzel is making his PGA Tour season debut.
"Bill shooting 7-under is incredible out there," said the reigning U.S. Open champion Simpson. "I mean, it was very tough. I felt like my 3-under was pretty good."
Overnight co-leaders Fredrik Jacobson and Sang-Moon Bae both failed to maintain the pace on Saturday. The former got caught in the high, dry kikuyu grass on the par-4 fifth and stumbled to a double bogey before eventually ending with a 72.
World No. 3 Luke Donald, who is also making his PGA Tour season debut, shot 70 and moved into a tie for fifth place with Jacobson at 8-under.
Josh Teater (68) and Charlie Beljan (68) are 7-under, Hunter Mahan (68) and Sergio Garcia (69) are 6-under, and Adam Scott (70) is 5-under. Garcia was in second place at the end of the opening round.
Bae, meanwhile, tumbled to 4-under with a third-round 76. The second-year player from South Korea had five bogeys and a double-bogey against just two birdies on Saturday.
Mickelson, Bradley and world No. 8 Lee Westwood are 3-under through 54 holes.
Haas is looking to build upon his two previous starts, where he tied for ninth at Farmers Insurance Open and ended knotted in sixth at Waste Management Phoenix Open.
On Saturday he opened with four straight pars before picking up three birdies over his next five to join Schwartzel atop the leaderboard at 8-under. Then it was on to the par-4 10th, where Haas clinched last year's win with a 40-foot birdie putt on the second playoff hole.
This time the 10th again proved kind, as Haas chipped in from 57 feet for eagle and a 2-stroke lead. He followed with a birdie at the 11th to open up a 3-shot advantage over a revolving group fighting for second place.
After a run of pars, Haas tallied another birdie at the 17th to reach the clubhouse at 12-under.
"I think I've just got to try to stay in the moment, don't let my emotions get the best of me," said Haas, who is seeking his fifth PGA Tour win. "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."
With Haas off the course, Merrick appeared poised to secure sole possession of second place when he birdied the 17th to reach 10-under, but he bogeyed the last to join Simpson and Schwartzel.
NOTES: Haas will attempt to join Ben Hogan, Arnold Palmer, Paul Harney, Mike Weir, Corey Pavin and Mickelson as the only back-to-back champions at Riviera ... Scott, the 2005 champion at this event, is making his season debut ... Graeme McDowell, who was making his season debut, Dustin Johnson, Zach Johnson and Bubba Watson were among those that missed Friday's cut.