Tiger Woods gave himself the chance to stage the third biggest last-day comeback in Masters Tournament history as he dazzled while Rory McIlroy struggled early on.
Seven behind the 21 year old Northern Irishman when he resumed, Woods went to the turn in a fantastic five under par 31 that was only one off the tournament record.
And with McIlroy bogeying the first and fifth in a nightmare opening, the pair were level on ten under par - and they had South African Charl Schwartzel alongside them after he chipped in at the first and pitched in for eagle at the third.
So if anybody thought McIlroy was in an unassailable position when he teed off four clear of the field they were quickly made to think again.
McIlroy three-putted the first for bogey, struggle hard for a par five on the next after going in two bunkers and then missed from three feet for a five at the 455 yard fifth.
Woods had teed off an hour earlier, but after making four at the long second he pitched to three feet on the next - not as good as Schwartzel, but still pretty good.
A three-putt bogey on the short fourth appeared a bogey he could ill-afford, but then came further birdies at the sixth and seventh, both from eight feet, and on the uphill 570 yard eighth he moved into overdrive.
His second shot ran up to ten feet and in went the eagle putt before he salvaged a miraculous par at the next, going from pine straw in the trees to a greenside bunker and holing from 15 feet.
And all this, of course, after 17 months and 20 events without a victory as he dropped from World Number One to seventh in the rankings.
Luke Donald was in the hunt too, making birdie at the second and responding to a bogey at the seventh with a four on the eighth to be only two behind and joint fifth.
Fellow Englishman Ross Fisher was two further back after also making birdie at the eighth.
However, last year's runner-up Lee Westwood, having turned in 33, looked to have fallen out of the race when he double-bogeyed the short 12th.
He was four under with Scot Martin Laird, who playing with Woods was watching some sparkling stuff even if he was not able to match it. He was out in a level par 36.
McIlroy badly needed something good to happen for him - and it came with a 15 foot birdie putt on the seventh.
At 11 under he was one ahead and things got better when Woods then three-putted the short 12th, missing from three feet.
Schwartzel was alone in second, but he missed out on a birdie at the eighth when his second shot kicked right and he failed to get up and down.
Woods, meanwhile, slipped into a tie for third with Australian Adam Scott, who birdied the seventh and eighth, Korean K J Choi and Argentina's 2009 champion Angel Cabrera.
Woods played a poor chip and could only par the reachable 13th, but it was not as bad as the chip McIlroy hit on the eighth.
A duff from over the green meant he had settle for par and after another on the ninth for an outward 37 - he was the only player over par on the day in the top 19 - he turned one in front of Schwartzel, Choi and Cabrera.
Woods was two back with Scott and also Donald, who made a seven foot birdie putt at the difficult tenth.
McIlroy was hoping for much better things on the famed back nine, but instead went from bad to worse.
His hooked drive hit the trees and flew over in between the cabins way left of the fairway - and not far from the tee.
After his next shot he still needed a wood, but went left with that as well, then with his pitch caught another tree. After a chip and two putts an ugly triple bogey seven went on his card and suddenly Schwartzel, Cabrera, Scott and Choi were joint leaders and McIlroy eight under and down to seventh.
Donald's hopes nosedived as well when he went in the water at the 12th and double-bogeyed to be three behind.
Woods was only one behind now and set up the chance of another eagle with a towering iron to four feet on the long 15th.
