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 golf course. Solid iron shots led to a pair of birdies on the front nine, and with Riviera playing tough in warm, dry conditions on 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 a 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, and it was nearly eight shots better than the average score. It put Haas at 12-under 201, leaving him in good position to become only the eighth back-to-back winner in the 76-year history of this tournament.All he cares about Sunday is winning."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."A year ago, Haas was two shots behind going into the final round and wound up winning in a playoff over Mickelson and Keegan Bradley. This time, he has a comfortable margin over U.S. Open champion Webb Simpson and former Masters champion Charl Schwartzel, who each thought they did well for a 68.John Merrick bogeyed the 18th hole for a 70 and joined Simpson and Schwartzel at 9-under 204.Luke Donald overcame a sloppy start - 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 Fredrik Jacobson (72).Mickelson was hopeful of making a move and instead went the other direction. He missed three par putts of about 6 feet on the front nine and had a 72, putting him nine shots behind. Ernie Els, playing with Mickelson, also dropped shots early and dropped out of the hunt with a 73.The round started with 20 players separated by five shots. Thanks to Haas and his flawless play, only eight players were within five of the lead.It might not be easy for anyone to catch up to Haas if the sunshine continues to bake Riviera. The fairways were so firm that tee shots were running some 50 yards after they landed, and the greens were firm enough that balls ran out an extra two feet around the hole."I had a lot of 3- and 4-footers for par," Simpson said.He was pleased with his round of 68 that included only one bogey, but when Simpson pulled out his cellphone to check the leaderboard as he sat down for lunch, he saw Haas on top with a 64."So he played great," Simpson said.Most impressive about how Haas has gone around Riviera in the last few days is 40 consecutive holes without a bogey. The last one he made was on Thursday when he missed a 4-foot putt.But on this day, it was his birdies and one eagle that made the difference."I was just kind of plugging along out there and then all of a sudden, made a nice putt at 9, chip-in at 10, good up-and-down at 11," he said.And off he went.The birdie putt on the ninth was about 30 feet, and Haas had to play it outside the hole and hit it with purpose. It broke sharply into the cup, and then he hit 3-wood off the tee on the 10th, leaving it some 10 yards short of the green with the left pin. He had seen Greg Chalmers play a pitch from about the same area to 6 feet short of the hole and figured that was a good play - anything that rolled by the hole was likely to keep going off the green and down into a valley.Haas hit an even better shot, landing it about 15 feet short of the hole and watching it roll into the cup. He hit his second shot into a bunker near the green on the par-5 11th and got that close for birdie, and later in his round, he splashed out of the sand on the par-5 17th to inside a foot for his final birdie.Simpson, who arrived at Wake Forest the year Haas graduated, figures Haas will have to make a few mistakes for anyone to make a big move."I think Bill is in a position, if he keeps a three-shot lead and goes and plays well again, that it's going to be hard to catch him," Simpson said. "But with the golf course this tricky, you get a guy that has a good front nine, he could be tied or even in the lead with nine to go. So anything can happen tomorrow."Schwartzel is the only player with all three rounds in the 60s. He made two mistakes, one of them more of a bad break. His tee shot on the 10th bounded through the green with such pace that it stayed toward the back slope of the rear bunker. His shot came out too soft and rolled back off the green, leading to bogey.He came out weakly from the sand on the 15th and had to make a 6-footer to escape with bogey."It's easy to make bogeys," Schwartzel said. "The course got a bit firmer and, playing in the last few groups, the greens get a bit more bumpy. So it's hard to make birdies and also to keep the bogeys off the card.""I probably won't change anything," he said. "Just keep playing the way I am and see if I can give myself chances and see what happens. I know the game is good enough to be able to win tomorrow."DIVOTS: Sang-Moon Bae, who shared the 36-hole lead with Jacobson, took double bogey on the 17th hole and had a 76 to fall eight shots behind. ... Charlie Beljan, he of panic attack fame when he won at Disney, felt his heart race when he realized he would play with Mickelson and Els. Beljan beat them both with a 68, and then asked them to autograph his visor. ... Jacobson would have to finish alone in 19th place or better to avoid facing Tiger Woods in the opening round of the Match Play Championship next week. He was in a two-way tie for fifth. ... Lee Westwood fell nine shots behind with a double bogey on the par-3 14th and a bogey on the par-5 17th. He shot 74.