Tiger Woods fired two eagles in his last six holes to carry a one-stroke lead over England's Lee Westwood into the final day of the US Open.
Woods, 32, carded a one-under 70 for three under overall to edge past Westwood (70) on the last green on a dramatic day at Torrey Pines.
All of Woods's previous 13 major wins have come when he was leading going into the final round.
Westwood is aiming to become the first British US Open winner since 1970.
The 35-year-old is hoping to clinch a maiden major title at Torrey Pines and emulate the feat of countryman Tony Jacklin 38 years ago.
All of a sudden some pretty cool things started happening
Long-time third-round leader Rocco Mediate of America will begin one stroke further back with Australia's 2006 US Open champion Geoff Ogilvy and American DJ Trahan another shot adrift.
But the history books show that Woods has never failed to clinch a major when holding at least a share of the lead ahead of the final round.
And at times his golf on Saturday suggested there was a higher presence at work.
Woods began one shot off the pace of Australian Stuart Appleby and immediately made a double-bogey on the 1st.
He dropped another shot on the 4th and, though he regained it at the 7th, he was fighting some wayward driving and a left knee which was giving him increasing problems following a two-month lay-off after surgery.
Westwood is aiming to become the first British winner for 28 years
The first sign of the brilliance to come was an eagle three, courtesy of a monster 60ft putt at the 13th after an errant drive into the rough.
A bogey followed after yet another poor drive and he crouched to clutch his knee on the 15th tee before soldiering on to card a couple of pars.
But he chipped in for a birdie from the rough surrounding the green on the 17th and drained another lengthy effort for an eagle three on the 18th to overhaul Westwood.
"I was just trying to get back to even par, somehow," he said.
"I felt that would be somewhere near the lead. All of a sudden some pretty cool things started happening."
Westwood, up ahead, withstood the pressure of "moving day" to edge coolly pass Mediate, who led by as much as three shots at four under at one point.
I'll just stick to my own game plan and try to keep doing the things I'm doing
Afterwards, the Englishman insisted he was unfazed about playing alongside Woods in the final pairing on Sunday, despite plenty of his peers wilting in the spotlight over the years.
"It's what I spend so long on the range for," said Westwood, whose best US Open finish was tied for fifth in 2000.
"My goal at the start of the week was to get into contention and I've done that. I had a lot of inner calm and I was very patient.
"I've played against Tiger loads of times, especially in Ryder Cups, and you're not going to get more highly pressurised than that.
"If you let it get to you, then you have problems. But I'm a fairly calm person and fairly level-headed, so I'll just stick to my own game plan and try to keep doing the things I'm doing."
Westwood, who plummeted from fourth in the world rankings into the 200s during a prolonged slump, is now back up to number 20.
He has won 29 tournaments around the globe and just once on the US PGA Tour. "So I've proven I can win," he said.
Woods added: "We're going to have a lot of fun out there."
In-form Europeans Robert Karlsson of Sweden and Miguel Angel Jimenez of Spain will start five shots adrift alongside Australian Robert Allenby, American Hunter Mahan and Colombia's Camilo Villegas.
And two-time champion Ernie Els of South Africa, former Masters champion Mike Weir of Canada and Spain's Sergio Garcia have an outside chance at three over.
But second-round leader Appleby slid away after a round of 79, England's Luke Donald disappeared after a 77 and San Diego local and world number two Phil Mickelson ran up a quadruple-bogey nine at the long 13th and ended nine over to destroy his challenge.
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