Luke Donald is tied for fourth after the third round of the Buick Invitational at Torrey Pines.
Donald hit a 71 to sit level with American Paul Goydos – who carded a 72 – in fourth, six shots off the pace at one under as John Rollins climbed into a three-stroke lead.
However, reigning British Open and PGA champion Padraig Harrington double-bogeyed number four and bogeyed number seven and could not make up the deficit on the back nine, carding a 74 for the second straight day and slipping to 15 shots off the pace in a tie for 48th.
Harrington is playing in his first tournament of the season after having two non-malignant melanomas removed from near his right eye.
Rollins birdied the second, fourth and sixth holes and traded two birdies and three bogeys on the back nine to move three shots ahead of Camilo Villegas with an overall score of 12-under-par 204.
Rollins is bidding for his first title since the 2006 BC Open.
Villegas had started with a one-stroke lead but bogeyed number seven and double-bogeyed number nine to go out at three over 39.
The Colombian, who won twice on tour last season, appeared to have trouble with rainy and windy conditions early in the day and finished at two over 74.
American Nick Watney sits alone in third place after carding a one-under-par 71 yesterday. Watney started the day in fourth and used a birdie on 17 to jump up a spot.
American Charles Warren was the big mover of the day, jumping from 32nd to a tie for sixth place with a four-under-par 68. Warren did much of his damage on the back nine, coming in at 33.
Lucas Glover carded a three-under-par 69 and Charley Hoffman, who began the day in third place, slumped to a two over 74 to join Warren at seven shots back.
Phil Mickelson, who has won this event three times, bogeyed three of the first 11 holes and finished with a one-over-par 73 on the day to leave him at one under for the tournament.