Campbell, who led by four shots overnight, is through four rounds at 24-under-par 264. It's the best 72-hole score of his five-year PGA Tour career, but Scott Verplank made things close heading into the final round by firing an 8-under 64 to get within a stroke.
Two-time champion Phil Mickelson, who is playing in his first event of the new season, chipped in twice during his round and shot a 67 to end the day tied for fourth place at minus-18. Justin Rose joined Mickelson there after a 6-under 66.
The first four days of this 90-hole event were spread out over four courses: Classic Club, La Quinta, the Palmer Course at PGA West and Bermuda Dunes. The final round will be played at the Classic Club, a new course added to the rotation this year which has played the toughest over the first four days.
Mickelson, for one, planned to practice his putting at the Classic Club before the final round begins Sunday. But the course, studded by water and sand, may be too tough for those who need to make up more than just a couple of strokes on Campbell.
'Where you can make up ground is if the wind blows and your opponents make big numbers,' Mickelson said. 'I think you can shoot 3, 4, 5 under par. But to make up a six-, seven- or eight-shot lead, that will be tough without the leaders coming back.'
Campbell played his fourth round at the Classic Course, so its layout will be fresh in his head when he tees off Sunday.
'I think that helps,' said Campbell, who admitted that his round Saturday was easier than some of the others played at the Classic Club when high winds were a factor.
'I think more than anything, we got it on a nice day,' he said. 'The guys on Wednesday and Thursday, they got a little bit of a bad draw. But that's the way it goes, I guess.'
Campbell continued his assault on par-5s Saturday, carding the first of his six birdies at the par-5 fourth to get to minus-20. He eventually made the turn at 23 under after birdies at six, seven and nine.
After extending his lead to six shots with another birdie at the 10th, where he made a 15-foot putt, Campbell stumbled to a bogey at the 11th -- just his second bogey this week. He made that shot up with a birdie at the par-5 14th, which put him at 15 under on par-5s for the tournament.
Campbell's lead was just two strokes when he hooked his tee shot into the rough at the par-4 16th. While Verplank was closing quickly at Bermuda Dunes, Campbell scrambled from the tall grass and rolled in a 6-foot par putt to remain at 24 under.
Verplank, who has four PGA Tour wins, but none since 2001, pulled within a stroke for the first time when he made a 4-foot birdie putt at Bermuda Dunes' par-4 14th.
He gave that shot back with a bogey at the 17th to fall two off the pace, but got back to within one at the 18th when he chipped to tap-in range for a birdie, his ninth of the day.
'I think what I did today would probably be a nice blueprint for what you do every day out here,' said Verplank.
Campbell will be trying for his third win on the PGA Tour, and first since the Bay Hill Invitational in March 2004. His best and worst fifth-round scores both came at this event, a 65 in 2002 and a 77 in 2003.
The 30th-ranked player in the world, Campbell beat his lowest 72-hole score by a stroke. Chalk that up to his 15-under performance on the par fives this week.
'I think that's key in this tournament.' Campbell said. 'A lot of them, you knock it on in two...and I've been able to make birdie on most of them.'
Former champions Mike Weir (66) and Jesper Parnevik (62) lead a group of six players tied for sixth place at 17 under.
The cut fell at minus-7, and among the 47 players missing the final round will be Davis Love III, 2005 Rookie of the Year Sean O'Hair and fan favorite Jason Gore.