Alex Cejka vaulted into third place with 11 points in the third round to move within one point of the leaders. Tom Pernice, Jr. also posted 11 points Saturday to move to 26 points, where he shares fourth place with Bob Tway (eight points).
For the first time in three days there were no delays as the field managed to finish Round 2 and play the entire Round 3 on Saturday. Pampling, for one, played 25 holes on Saturday alone.
Pampling started the third round nine points behind DiMarco. DiMarco however came back to the field quickly at Castle Pines Golf Club.
He opened with a 6-foot birdie putt at the par-5 first to move to 33 points. Things went downhill quickly, though.
After dropping a point with a bogey at the third, DiMarco left his second shot in a greenside bunker at the par-3 fourth. He managed to get up-and-down for bogey, but slipped back to 31 points.
The 35-year-old DiMarco settled down to par the next two holes, before finding more trouble at the eighth. He lost his second shot way right into the trees. After a pitch out, he nearly holed out for birdie as his fourth shot landed within inches off the cup.
His ball came to rest some 10 feet from the hole however and he missed his par putt to drop another point. DiMarco found the water off the tee at the next, and that led to another bogey that dropped him to 28 points.
Pampling, meanwhile, picked up four points with two front-nine birdies to climb to 26 points. Around the turn, DiMarco continued to struggle while Pampling move into the lead.
DiMarco, a three-time winner on the PGA Tour, dropped another point with a bogey at the 12th. That dropped him to 27 points. Pampling, playing alongside the struggling DiMarco, rolled in a 15-foot birdie putt at the par-4 13th to claim the lead with 28 points.
DiMarco fought right back to birdie the par-5 14th from 3 feet to reclaim first place at 29 points. He faltered to a bogey at the next after he spun his ball off the green and into water to fall into a share of the lead with Pampling.
Pampling then tripped to a bogey at the par-3 16th to fall one behind DiMarco. Both players picked up birdies on the par-5 17th. DiMarco then tripped to the eighth bogey of his round at the last to drop into a tie for the lead heading into the final round.
'I drove it okay, but I hit some poor irons shots,' said DiMarco. 'I was lucky, believe it or not, not to make a couple of double-bogeys out there. I made a couple of good 10-footers for bogeys on Nos. 4 and 15, and then hit it in the water on nine and was able to make bogey there too. It could have been worse.'
DiMarco has held the lead entering the final round on four occasions. On one of those four occasions, DiMarco went on to win -- at the 2000 SEI Pennsylvania Classic.
'I'm going to play my game tomorrow,' DiMarco said. 'I know if I go out and make five or six birdies and play consistent like I did the first day, guys from the back are going to have to shoot a really low number.'
Pampling will go for his first PGA Tour title on Sunday. His best previous finish is a tie for third at the 2003 Reno-Tahoe Open.
'I feel good. It was an interesting day,' Pampling said. 'Obviously Chris struggled all day, but he hung in there and obviously we're tied still. I think it's the first time I've been third-round co-leader anyway so hopefully it will be a charm.'
Jose Maria Olazabal picked up nine points Saturday to move to 23 points, where he stands alone in sixth place. Stewart Cink, Arron Oberholser and Tim Petrovic are one point further back at 22.
Defending champion Davis Love III heads a group of six players with 21 points. He is joined there by Danny Ellis, Jay Haas, Todd Hamilton, Rocco Mediate and Justin Rose.
This event had a second cut that allowed the final 36 players and ties to move to the final round. A total of 44 players survived to play the final day.