Ames was steady on Saturday, when the wind kicked up considerably, making the Pete Dye design extremely difficult. There were only three birdies recorded at the famous island green, par-3 17th and one at the closing hole as greens became very slick.
This year's winner at Pebble Beach, was tied for the lead with Ames as he moved to the 17th tee. He found water, made triple-bogey, drove into more water at 18 and made double-bogey. He lost five shots, and when Ames birdied 16, Oberholser fell six off the lead.
'I made a bad club choice and one poor swing and it added up to 6-6 on the last two holes,' said Oberholser. 'I'm not the first person that's done that, and I certainly won't be the last.'
Some handled the final two holes better than others.
Vijay Singh, the world No. 2, posted one of the three birdies at 17 en route to a 2-under 70. He finished at 8-under-par 208 and is tied for second place with Saturday's playing partner Sergio Garcia, who also carded a 2-under 70.
Former Masters champion Mike Weir, who holed his approach for an eagle at four, shared honors for lowest round of the day with a 4-under 68. He is knotted in fourth place with Henrik Stenson, who aced the 13th hole Saturday. Stenson, who is second on the European Tour Order of Merit, bogeyed his final two holes for a 70, but joined Weir at minus-6.
Tiger Woods, the 2001 Players Champion, mixed five bogeys and four birdies for a 1-over-par 73. The reigning Masters and British Open champion is tied for 23rd place at 2-under-par 214.
Woods is seven back and on a course that is playing as difficultly as the TPC at Sawgrass, he will have a tough time catching Ames, who he trounced 9 and 8 in the opening round of this year's WGC-Accenture Match Play Championship.
Ames trailed Jim Furyk by a stroke heading into Saturday's third round, but made up the deficit quickly with a 13-foot birdie putt at the first. He parred his next three holes, which was enough to keep him atop the leaderboard.
Ames found trouble with his tee ball at the par-4 fifth. His ball landed in the rough near a trap and Ames was forced to hit his second with the ball about belt high. Ames hit his approach into the left rough, then played an awkward pitch 15 short of the flag.
He rolled his par putt almost 3 feet past the hole, but missed that putt coming back. Ames walked off with a double-bogey 6 and fell two behind Singh.
Every player fell down the leaderboard throughout the round, so Ames never trailed by an insurmountable margin. He birdied the 10th, then hit his third to a foot to set up a tap-in birdie at the par-5 11th. That birdie brought Ames to 8 under par, but he still trailed by a stroke.
He got into a tie for the lead, but fell quickly when his 7-iron tee ball came up short and right of the putting surface on the par-3 13th. Ames atoned for the mistake with a 15-foot birdie putt at the 14th to match Oberholser in the lead.
Oberholser collapsed as Ames finished his back nine, but Singh and Garcia both got to minus-8. Garcia two-putted from 40 feet for a birdie at the par-5 16th, while Singh rolled in a 4-footer for birdie at 17.
Ames broke into the lead at the par-5 16th. His drive landed in the fairway, but his second found a left, greenside bunker. Ames blasted out to 3 feet and converted the birdie try.
Ames hit a 9-iron to 26 feet at the 17th, but had a very fast putt. He lagged it inside 3 feet and holed the par putt.
At the closing hole, Ames once again drove into the short grass and had 185 yards to the flagstick. Pat Perez had been the only player to record a birdie at 18, but Ames took dead aim. His ball ran just past the hole to 11 feet, where Ames over-played the break. He tapped in for par and his fourth 54-hole lead on the PGA TOUR.
Ames won once in the previous three tries, the 2004 Western Open. He also finished as runner-up at this event in 2002, when Craig Perks posted a wild victory than including a pair of chip-ins on the back nine on Sunday.
'I just want to go out tomorrow, and play the same way I did today,' said Ames. 'Commit to everything like I did today and hopefully things will work out in my favor.'
Furyk fell quickly with a double-bogey 7 at the second and a bogey at No. 3. All tallied, the first and second-round leader collected two double-bogeys, five bogeys and six birdies for a 3-over 75.
He is tied for sixth place with two-time U.S. Open champion Retief Goosen (71), Carl Pettersson (70), Tom Pernice, Jr. (71), Bo Van Pelt (72) and John Rollins (72) at minus-5.
Adam Scott, the 2004 champion, was tied with Ames for second place at the start of the third round. He struggled to a 10-over-par 82 and is tied for 51st place at plus-3.