Tiger Woods gave himself the chance to stage the third biggest last-day comeback in Masters Tournament as he dazzled while Rory McIlroy struggled.
Seven behind the 21 year old Northern Irishman when he teed off, Woods went to the turn in a fantastic five under par 31 that was only one off the tournament record.
He then had his second three-putt bogey of the day on the short 12th but, when only one behind he hit a towering iron to four feet on the long 15th, a second eagle of the day was on the cards.
It was to take the outright lead, but his putting let him down again and by missing it and having to settle for a birdie Woods - without a win for 17 months and 20 events - was part of a five-way tie for the lead.
Alongside him were Australian Adam Scott, Argentina's 2009 winner Angel Cabrera, South African Charl Schwartzel and Korean K J Choi.
As for McIlroy, four clear of the field, overnight, he had slumped all the way to seventh by following a disappointing outward 37 with a horror triple bogey at the tenth.
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 before he chipped and two-putted for a seven.
Only two off the lead it was still all to play for the player trying to be the second youngest winner of the title in history - after Woods, of course - but when he three-putted the next for bogey all the energy appeared to have drained out of him.
McIlroy was down to tenth and three back. There was time to repair the damage, but it would require a superb effort and he was in danger of going down as the player who lost the biggest last-day lead in a Major since Jean Van de Velde at Carnoustie in 1999. He had been five clear.
Choi bogeyed the short 12th, but it was a five-way tie at the top again when Scott's compatriot Jason Day birdied 12 and 13 to go to ten under as well.
Woods had to settle for par on the short 16th, though, and he surely needed to birdie at least one of the final two holes just to have an opportunity of a fifth Green Jacket and 15th Major.
Sadly McIlroy's nightmare was not over. He four-putted the 12th for a double-bogey five and now was seven over for the round, five under for the tournament and in 11th place five off the lead.
He did not have a three-putt in the first 64 holes and now had taken seven in two holes.
It brought back memories not just of Van de Velde, but also of Greg Norman going from six clear to five behind Nick Faldo with a closing 78 in 1996.
He was not alone in finding it tough going, though. Luke Donald was only two behind when he went in the water on the 12th and double-bogeyed.
Cabrera bogeyed the 12th, but when Geoff Ogilvy completed five birdies in a row from the 12th it was a five-way tie again - and three of them were trying to take the title to Australia for the first time.
The deadlock was broken when Scott converted an eight foot chance at the 14th.
Woods had to settle for three closing pars for a 67 and set a ten under target, matched minutes later by Ogilvy. They were one behind, but were certainly not going to be leaving, especially when Scott hit a wild second right of the 15th green and missed the birdie chance on offer there.
Donald was back in it as well when he followed birdies at the 13th and 15th with a ten footer on the 16th to be only one behind, but it was not to be for last year's runner-up Lee Westwood.
A 70 left him five under, while defending champion Phil Mickelson's 74 put him only one under.
Schwartzel got up and down from just over the back of the 15th to join Scott on 11 under - but only for a few seconds.
Scott had hit his tee shot to the 16th a mere 18 inches from the cup and in it went for a one shot lead again.
Donald appeared out of it again when he three-putted the 17th for bogey and when his approach to the last hit the flagstick and rebounded off the green it looked over once more.
Incredibly, though, he chipped in to join Woods and Ogilvy.
As that happened Scott hooked his drive down the 17th and finished in a bunker on the adjoining seventh, while Schwartzel sank a 15 footer at the 16th and joined Scott again.
It was the 14th change at the top since the round began.
