Jose Maria Olazabal leads the pack of big names chasing Tiger Woods after a third-round 68 took him to within one shot of the leader at ten under.
The 1995 winner is one stroke clear of Retief Goosen and Colin Montgomerie, while Vijay Singh and Sergio Garcia are also within striking distance.
Olazabal landed a 40ft putt at the 12th for an eagle to ignite his challenge.
A bogey at the 13th spoiled things, but birdies at the fifth, ninth and 18th kept the momentum going.
The Spaniard said the prospect of partnering Woods in Sunday's final round did not worry him.
"I've always said I have no problem playing with Tiger," said Olazabal.
"I'm not sure I'm going to be as relaxed if I'm leading the event teeing off the 17th on Sunday, but I'll try to have as much fun as possible.
"There's always pressure but if you can manage to enjoy what you are doing that's a great step forward."
South Africa's Goosen is also in the running after a superb third round of 66 moved him to nine under.
The world number five started the day well down the field, but took heart from a birdie at the first.
A bogey at the fifth checked Goosen's progress, but he soon found form with three birdies before the turn.
Four more birdies on the back nine saw Goosen's challenge regain momentum despite a dropped shot on the 17th.
Goosen said his surge up the leaderboard was a result of his vastly-improved putting.
"I read the greens a lot better and that's what counts," Goosen told BBC Sport.
"I hit some good iron shots and that gives you a chance. You get into a mode where everything seems to flow and you see the shots a lot better."
Brad Faxon produced a third round of 70 to move to eight under and a share of fifth place.
The American, who had to come through qualifying to make the championship, endured a double bogey at the fourth.
But he soon got his round back on track with birdies at the fifth and sixth.
An inconsistent round saw him drop shots at the eighth and 15th, but he continued to battle away and was rewarded with four more birdies.
Garcia joined Faxon on eight under after a round of 69.
He got off to an inauspicious start with a bogey at the first, but redeemed himself straight away with a birdie at the next hole.
Another birdie at the fifth was followed by an eagle at the ninth.
Bogeys at the 12th and 16th took the gloss off, but birdies at the 14th and 18th kept him in the running.
Singh and Michael Campbell will have to produce something special to put pressure on Tiger Woods after they both ended the third round at seven under.
Fiji's Singh produced a mixed bag in his round of 71 with six birdies - including three in a row before the turn - sharing space with five bogeys on his scorecard.
Meanwhile, Campbell, who made seven birdies, said his round of 69 proved his surprise US Open victory last month was not a fluke.
"To come back after winning a major championship, a month later to play so well again proves I'm not just a flash in the pan," said Campbell.
"The experience will hold me through if I'm in the running for another major."