Graeme McDowell is in prime position to claim his second US Open title in California after a sublime back-nine earned him a share of the lead heading into the final round.
The 2010 champion capped an inward 34 with a birdie at the last to post a 68 and move to one under alongside Jim Furyk, while Tiger Woods went in the wrong direction on "moving day".
Lee Westwood matched the best round of the day, a five-birdie 67 giving him another legitimate shot at breaking his major duck, while two-time winner Ernie Els also surged into the mix after a remarkable last 12 holes.
Woods began the round tied at the top with Furyk and David Toms, but the 14-time major winner found fairways hard to come by as he bogeyed four of the first eight holes.
A birdie at the ninth steadied his round, but he dropped further shots at 16 and 18 to card a 75 and slip five behind McDowell and Furyk.
McDowell began with eight solid pars before a poor drive at nine cost him a shot, but he bounced back with birdies at 10 and 13 before converting a pure approach to six feet at the last.
McDowell said: "The ninth was a wake-up call. I realised my swing was getting quick and snatchy.
"Then the save on the 12th was huge. I thought I was in the bushes over the green, but making four spurred me on.
"I am firing pretty much on all cylinders. The key is not looking at leaderboards. It's not just me and Jim. There are a lot of guys who can win."
McDowell's time in the outright lead did not last long as Furyk atoned for a six at 16 with a birdie at the next as he handed in a workmanlike 70 to remain at one under.
Freddie Jacobson is the closest challenger two shots adrift after a 68 which included three straight birdies to finish off the tough front nine, while Westwood and Els are one further back on two over.
Westwood birdied five and seven only to bogey the next two, but he atoned with birdies at the 10th and 11th before nailing a 30-footer for a closing three.
Els looked out of the hunt when he bogeyed three of the first five holes, but he re-ignited his challenge with birdies at seven and eight, and he picked up another at 12 before pitching in from 50 feet for eagle at the 17th.
Nicolas Colsaerts was one for the day under after an exemplary first 14 holes before mistakes at 15 and 16 dropped him into the group at two over, although the Belgian will no doubt be happy with a 71.
Webb Simpson, Kevin Chappell and John Senden all posted 68s to move to three over alongside John Peterson, who celebrated the shot of the day when he aced the 199-yard 13th.