PACIFIC PALISADES, Calif. -- Hunter Mahan has given a shot back with a bogey at the 15th hole.

Mahan missed the fairway left and did the same with the green, then was unable to covert from 11 feet for par. So he's back in a four-way tie for second with Charlie Beljan, Webb Simpson and Charl Schwartzel.

Of the five players at the top of the leaderboard, the two major champions have the most holes remaining. Simpson and Schwartzel are in the day's final pairing with overnight leader Bill Haas.

PACIFIC PALISADES, Calif. -- A two-stroke swing has put Hunter Mahan and John Merrick back into a tie at the top of the leaderboard at the Northern Trust Open.

Mahan moved to 11 under with a 23-footer at the 14 hole minutes before Merrrick made bogey at No. 13 after missing the green to the left and failing to convert a 13-footer to save par.

Charlie Beljan, Webb Simpson and Charl Schwartzel -- the latter two playing in the day's final group -- are one stroke behind at 10 under. Fredrik Jacobson and overnight leader Bill Haas are tied for sixth, another stroke behind.

PACIFIC PALISADES, Calif. -- John Merrick is looking to author a Cinderella story at the Northern Trust Open.

Merrick, who was raised and still lives in Long Beach and graduated from UCLA, has a two-stroke lead with seven holes remaining in his hometown event.

Merrick, who is looking for his first victory in seven years as a PGA TOUR member, just birdied the 10th and 11th holes to slip past Hunter Mahan. He made a 14-foot birdie putt at the 10th hole and got up-and-down from the greenside bunker at No. 11 to move to 12 under.

Minutes after Merrick birdied the 11th, Mahan three-putted the 12th from 29 feet, missing a 7-footer to save par. So Mahan is now tied for second with Fredrik Jacobson, Bill Haas, Webb Simpson and Charl Schwartzel at 10 under.

PACIFIC PALISADES, Calif. -- The 10th hole had been pretty darn good to Bill Haas of late. Until Sunday, that is.

After all, that's where he rolled in a 45-foot birdie putt to beat Phil Mickelson and Keegan Bradley in the playoff last year. Haas had played the driveable par 4 in 3 under this week, too, including an eagle on Saturday.

Sunday, though, Haas drove it left and sent his second shot across the green into the bunker. When he was unable to get up and down for par, Haas fell a shot behing Hunter Mahan and John Merrick, who now lead at 11 under.

Haas, who led by three entering the final round, is now tied at 10 under with his two playing partners, Webb Simpson and Charl Schwartzel, along with Fredrik Jacobson.

PACIFIC PALISADES, Calif. -- For the first time all day, Bill Haas no longer owns sole possession of the lead at the Northern Trust Open.

John Merrick, who lives in nearby Long Beach, just made a 14-footer for birdie at the 10th hole, which is playing to 312 yards today, to join Haas at 11 under. Merrick, a UCLA product who is playing in the penultimate group, is looking for his first victory in seven years at a PGA TOUR member.

Haas, who fired a brilliant 64 on Saturday, just made the turn in 1 over. Hunter Mahan, Fredrik Jacobson and Webb Simpson are one stroke behind the leaders.

PACIFIC PALISADES, Calif. -- Consecutive bogeys at the seventh and eighth holes have turned Bill Haas' comfortable three-stroke lead into one.

Haas found a fairway bunker, then chunked a chip at the eighth hole, leaving himself 35 feet for par. When he two-putted for just his fourth bogey of the week, Haas dropped back to 11 under.

Charlie Beljan, Hunter Mahan, John Merrick and Fredrik Jacobsen are Haas' nearest competitors after making the turn in 32 31, 34 and 33, respectively. Webb Simpson was also at 10 under until he hit his drive at No. 8 well left and into a bush, where he had to take a drop on the way to a bogey.

Simpson is tied with playing partner Charl Schwartzel, who is even for the day, at 9 under.

PACIFIC PALISADES, Calif. -- Hunter Mahan, who defends his title at the World Golf Championships-Accenture Match Play Championship next week, has gotten into the mix at Riviera.

Mahan has birdied four of his first six holes to move to 10 under and into a tie with Fredrik Jacobson. He made a 9-foot putt at the first hole, then added a 13-footer at No. 2, a 40-footer at the fifth and anoher from 13 feet at No. 6.

Bill Haas remains in the lead at 13 under after completing five holes in the final round of his title defense.

Mahan has had a solid start to the season, finishing 16th or better in his last three starts. Interestingly, his best finish at the Northern Trust Open in seven appearances is a tie for 17th in 2009.

PACIFIC PALISADES, Calif. -- Bill Haas' lead is now just two after he made his first bogey in 42 holes at the second hole on Sunday.

Haas drove into the tree-lined right rough and then put his his second shot into the right greenside bunker. He blasted out to 8 feet but missed the putt for par to drop back to 12 under, which is where he started the day.

Haas, who had two-putted from 37 feet for birdie at No. 1, bounced back quickly, though, when he drained a 30-footer at the third hole. His playing partner, Webb Simpson, answered with a 5-footer for his second birdie of the day to  move to 11 under.

The other member of the final group, Charl Schwartzel,  missed an 11-foot birdie putt at the first hole, which is playing the easiest on the course, and then lipped out a 7-footer for par at the second to fall back to 8 under.

Fredrik Jacobson is the only other player in double figures at 10 under after making birdie on two of his first three holes.

Bill Haas has a three-shot lead going into the final round at Riviera. (How/Getty Images)

By Brian Wacker, PGATOUR.COM

Bill Haas will have a familiar face alongside him in the final group: fellow Wake Forest alum Webb Simpson, who arrived on the Winston Salem, N.C., campus the year after Haas graduated.

But part of the reason Haas is playing in the final group goes back to some work he did on his swing with coach Billy Harmon and dad and Champions Tour player Jay Haas after the Humana Challenge in partnership with the Clinton Foundation.

"My swing looked lazy and I was getting ahead of it," Haas told Golf Channel Sunday morning. "I'm basically trying to hit it really high and a little harder. It's helped me stay behind it. Having a little more speed is key for me."

A third-round 64 certainly helped.

As for playing with Simpson, whom he leads by three? "It'll be an easy walk," Haas said. "I have to beat the golf course. We'll be grinding out there."

Haas and Simpson will tee off, along with Charl Schwartzel (also three back), at 1:30 p.m. ET.