John Merrick (back) of the US hugs his caddie Ryan Goble as he celebrates winning the Northern Trust Open golf tournament on the second playoff hole at Riviera Country Club in Los Angeles, Feb 17, 2013. [Photo/Agencies]

Fluctuating scoreboard

On another sun-soaked day at Riviera where the challenging par-71 layout ran fast and firm, the scoreboard fluctuated wildly as players repeatedly advanced and then stumbled.

Haas, three ahead overnight, made a roller-coaster start with birdies at the first and third and a bogey at the second moving him to 13 under and two strokes in front of playing partner Simpson.

Though Haas did well to save par at the short sixth, where he sank an 11-foot putt, he bogeyed the seventh and eighth for his lead to be cut to just one shot at 11 under.

He then safely parred the ninth to reach the turn in one-over 36, a stroke in front of Hunter Mahan, Merrick, Jacobson and Simpson.

However, Haas again stumbled with a bogey at the difficult 10th after his tee shot ended up well left of the target and his approach rolled through the green into the back right bunker.

Merrick, who had earlier birdied the 10th, edged a stroke clear when he sank a nine-footer to birdie the par-five 11th, before pumping his right fist in delight.

A bogey by Mahan at the par-four 12th handed Merrick a two-shot advantage but Mahan trimmed it back to one when he drained a 24-foot birdie putt at the par-three 14th.

Moments later, Merrick bogeyed the 13th after ending up in the right rough off the tee and missing the green with his approach to slide back into a share of the lead with Mahan.

Mahan's title bid unravelled as he bogeyed 15 and 17, and Jacobson made a late run with consecutive birdies, almost holing out with his approach at the par-four 15th and sinking a 14-footer at the short 16th to join Merrick at the top.

But Jacobson also faltered with his bogey at the last, leaving the stage clear for Merrick and Beljan to battle it out for the title.