Britain's Lee Westwood maintained ice-cool composure while fending off an electrifying back-nine charge by Phil Mickelson to take a one-shot lead after Saturday's third round of the US Masters.
While Tiger Woods clawed his way back into contention after losing his cool early on, Westwood fired a four-under-par 68 in glorious spring sunshine at Augusta National to post a 12-under total of 204.
Mickelson, a two-time Masters champion, carded a 67 to lie second with world number one Woods and his playing partner KJ Choi of South Korea a further stroke back at eight under after carding matching 70s.
Calm conditions, receptive greens and several accessible pins resulted in a glut of aggressive shot-making as the majestic Georgian pines at Augusta resonated with loud roars for birdies and eagles.
"It was probably one of those great days in golf at a major championship," Westwood told reporters after a well-crafted round featuring five birdies and a lone bogey at the 12th.
"You hear the cheers, but I didn't really pay any attention to it. I was well aware that somebody was making a charge, and I figured it was Phil.
"I think I'm ready," said the Englishman who is seeking a first major title after tying for third in his last two bids.
"I played really well out there and I felt very calm. All I can do is stick to my game plan ... and try and execute that properly."
In Sunday's final round, Westwood will have to execute in the company of Mickelson, who thrilled the crowds Saturday by covering 13, 14 and 15 with a stunning eagle-eagle-birdie run.
"I haven't played this way in a long time, and I feel great about my game," said the American, who briefly led by one before slipping back with a three-putt bogey at the 17th.
"I'm excited about Sunday. I think we are going to have some excitement, a real shootout. There are a lot of guys that are still in this."
Woods, playing his first tournament in nearly five months after his double life was exposed at the end of last year, was delighted to be in contention for a 15th major title.
"At one point I was seven back," the four-times champion said after being warmly greeted by the huge crowds as he made his way up the 18th.
"I really struggled with the pace of the greens and I was fighting my swing.
"To fight back there and to get it where I'm only four back right now was a pretty big accomplishment. I'm in good shape."
Mickelson, Masters champion in 2004 and 2006, treated the Augusta galleries to one of the most spectacular exhibitions of golf seen at the year's opening major.
He became only the third player to record successive eagles when he holed out from 141 yards at the par-four 14th, his ball pitching six feet beyond the hole before rolling back down the slope into the cup.
Mickelson, who had knocked in a six-footer to eagle the par-five 13th, raised his arms skywards in disbelief as the crowd packed around the green roared its approval.
"I can't believe that ball disappeared and went in," Mickelson said. "It was sure fun, especially after eagling 13, and that walk up was awesome."
Fellow-Americans Dan Pohl, in the third round of the 1982 Masters, and Dustin Johnson, in the fourth round last year, had previously posted back-to-back eagles at Augusta.
Mickelson came agonisingly close to a third successive eagle at the par-five 15th, his wedge approach there ending up six inches from the cup to give him a tap-in for birdie.
Woods made a flying start with long-range birdie putts at the first and third, closing to within a stroke of the lead before losing both momentum and his temper.
He bogeyed the fourth, sixth and seventh, his mounting frustration showing with a scathing "Tiger, you suck" after he made a poor swing on the sixth tee.
Watched for the third day in a row by his mother Kultida who wore a floppy white sun hat, Woods continued his up-and-down journey before ending the day with a curious mix of seven birdies and five bogeys.
He remains in the title hunt, however, after coming into this week with a major question mark hanging over his emotional state following revelations about his extra-marital affairs at the end of last year.
"That's what everybody wants to see," Westwood said. "Everybody has missed Tiger on the golf course the last five, six months and he's up there. Phil is up there. You've got four, three and one in the world on the leaderboard."