Defending champ Haas heats up at Riviera

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 weather.

"Temperature-wise, it's fabulous, but with that some of the fairways are really running out," Haas said. "The greens are difficult to hit and getting firmer and firmer. Just because it's playing shorter doesn't mean it's necessarily playing easier."

Haas's seven-under effort gave him a 54-hole total of 12-under 201.

Reigning US Open champion Webb Simpson and 2011 Masters champion 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.

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 Tour titles for Haas, who won the Tour Championship in 2011 to take the US circuit's $10 million playoff crown.

Haas's eagle gave him a two-shot lead and he 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.