Graeme McDowell surged into contention for a second US Open title in three years going into day four at Olympic.
The 32-year-old Northern Irishman shot 68 to finish one under alongside 2003 champion Jim Furyk (70) with Sweden's Fredrik Jacobson (68) two back.
Lee Westwood made his move for a first major with a 67 for two over with two-time champion Ernie Els (68), Nicolas Colsaerts (71) and Blake Adams (70).
Tiger Woods struggled from the start and carded a 75 to end four over.
Also on three over were 17-year-old amateur Beau Hossler, fellow Americans Jason Dufner, Webb Simpson, John Peterson and Kevin Chappell and Australian John Senden.
McDowell clinched his maiden, and so far only, major title down the California coast at Pebble Beach in 2010 and was followed to US Open glory by countryman Rory McIlroy last year. Victory for the man from Portrush would also mean a fourth major title in three years for Northern Irish players after Darren Clarke won the Open last year.
McDowell followed eight opening pars with a bogey on the 449-yard ninth at a hot and sunny Olympic Club in San Francisco.
But on the more scoreable back nine he holed putts of four feet on the 10th, 10 feet at the short 13th and then another four-footer for birdie at the last.
"It was hard work getting the right mindset," said McDowell, who clinched the winning point for Europe in the Ryder Cup at Celtic Manor in 2010.
"I can draw a lot from [Pebble Beach]. My emotions were the same as two years ago. If I can keep preparing for majors like I am doing, I'll put myself in position to win others so tomorrow's not the be all and end all."
The 42-year-old Furyk, who won his sole major at Olympia Fields nine years ago, was the joint third-round leader with Woods and David Toms (76) and held firm as his fellow Americans slipped back.
Woods, bidding for a 15th major title four years after his last, could not match the control and putting prowess of the previous two days and dropped four shots inside his first eight holes. A solitary birdie on the ninth was followed by bogeys at 16 and 18.
The 36-year-old has never won a major coming from behind going into the final round, but Lee Janzen came from five strokes back to win the last time the US Open was staged at Olympic in 1998. The biggest final-round comeback in US Open history was Arnold Palmer's seven shots at Cherry Hills in 1960.
"It was frustrating," said Woods. "I struggled on the greens quite a bit - they looked quick, but they putted slow.
"It was just one of those days where I was right in between clubs on about every single shot.
"I'm just going to have to shoot a good round, post early and see what happens.
"It's not like where you have to go out there and shoot 62 and 63. This is a US Open - you just need to hang around.
"I'm definitely still in the ball game. I'm only five back and that's certainly doable on this golf course for sure."
Westwood, playing in his 57th major, was four over through his first six holes on Thursday playing alongside McIlroy and Luke Donald but as the world's top two players missed the cut, the Worksop star edged his way into the tournament.
The 39-year-old followed up his opening 73 with a 72 before making his move from tied 29th, mixing two bogeys with five birdies including a 40 footer on the 18th.
Westwood missed out on the play-off by a shot in the 2008 US Open, and has had six other top threes in majors since then, including third behind McIlroy at Congressional last year.
"I think every time you get yourself in contention you learn something new," said Westwood, who was tied seventh at Olympic in 1998.
"I've been in contention a lot in different kinds of positions, leading, coming from behind. And in this tournament and other tournaments, the Masters, I finished third, so I was in contention there.
"I pick little bits out of all of those, but the main thing is just to go out there and believe that I'm good enough."
The last Englishman to win a major was Nick Faldo in 1996, while the only US Open winner from England was Tony Jacklin in 1970.
Jacobson, 37, who won his maiden PGA Tour event last year, has a best finish of tied fifth in a US Open, behind Furyk in 2003.
South Africa's Els, who chipped in for an eagle on the 17th, won the tournament in 1994 and 1997 and would break the record for the longest gap between US Open titles should he win on Sunday. Julius Boros (1952-63) and Hale Irwin (1979-1990) hold the record at 11 years.