Sweden’s Peter Hanson produced a brilliant third round 65 at Augusta National to lead Phil Mickelson by a shot going into the final day of The Masters Tournament.
On a dizzying third day in Georgia there were an amazing 16 changes at the top.
Hanson had the round of his life, a seven under par 65, and on only his second trip to Augusta National will start the final day nine under.
But, in a brilliant comeback from a poor start to the tournament, Mickelson refused to let the 34 year old Hanson, whom he beat in the singles of the last Ryder Cup, get clean away.
Trying to join Tiger Woods as a four-time winner of the title - Woods is unlikely to stop him from 38th place on three over - the left-hander had an eagle and four birdies in a back nine 30 that was only one outside The Masters Tournament record.
It gave Mickelson, who had been four over after ten holes of the year's first Major, a 66 - only one off his best-ever score in the event.
But Hanson, who was one shot lower, is the man who will have the advantage going into the final round of the season's first Major.
"I think it's going to be a very challenging day tomorrow," said the Swede. "It's going to be a long night and a long morning tomorrow. I think it's going to be great playing with Phil. We've played a lot of golf together, and it's just great to play in front of big crowds like it is here, and with all the support being behind him, hopefully it can feed off a little bit towards me, as well.
He added: "The last four or five holes today, everything seemed to be going right; It feels like you just have to make a good swing, make a good stroke and the ball seemed to just find the hole some way. It's just so nice to get into that zone or that peak performance, and I think I was pretty close to that today."
Hanson does not have a single top six finish in any Major to his name - his best was seventh in last year's US Open Championship, 11 shots behind McIlroy.
But he has four European Tour wins and one of them came in the penultimate event of the last Ryder Cup race and enabled him to take the last automatic spot in Colin Montgomerie's side.
He played with Mickelson in the first two rounds and was just ahead of him in a scintillating Saturday.
"I hear Phil make eagle on the 13th, but it just helps you a little bit to focus," he said, "and you have to make as many birdies as you can."
Hanson admitted, though, it might not be the easiest night he has ever had.
"I think it will be hard, but I'm just going to spend time with the family and get as much sleep as I can."
Mickelson has had an eagle - a curling 25 footer on the 13th to an almighty rorar - and 13 birdies since a triple bogey seven on the tenth in his first round.
"At some point I am going to get hot on this course, but I have to be in a position where it gets me onto the leaderboard.
"My finish on Thursday (two under for the last six for a 74) enabled me to do that.
"My putting has been so good, the best of my career probably."
There were also two shots of pure magic - a parachute chip at the 15th and an iron hooked round the trees onto the final green.
Mickelson has birdied the 18th all three days. He will be hoping he does not have to do it again to be crowned champion for the fourth time in nine years.
Hanson actually started with a bogey, but after birdies at the second, seventh and eight turned in 34 and then picked up five more shots in the last seven - and two in the last two.
South Africa's 2010 Open Champion Louis Oosthuizen is third at seven under following a 69, and then come Americans Bubba Watson and Matt Kuchar on six and five under respectively.
Padraig Harrington, Henrik Stenson and Lee Westwood are tied for sixth with Hunter Mahan on four under par,
Runner-up to Mickelson two years ago, Westwood was one back at halfway, but missed a par putt of little more than a foot on the ninth and had three other bogeys.
Four birdies, though, kept his hopes alive. US Open Champion Rory McIlroy looks to be too far back after he reached the turn in 42 with two double bogeys, including his second of the week on the first, and two bogeys.
When he finally made a birdie on the short 12th and struggling partner Sergio Garcia did the same the pair even shared a hug.
There would be another for the Northern Irishman on the long 15th and the last - in fact, he almost holed his second shot there - but with a 77 he had fallen all the way from joint third to joint 27th, and from one behind to ten adrift.
Only one player has come from that far back on the final day of a Major. Paul Lawrie, still three under here after a 72, was that man in the 1999 Open Championship.
Fred Couples and Jason Dufner, the two halfway leaders, were two more to struggle, both carding rounds of 75 to drop back to two under par.