Rory McIlroy jumped into a two stroke lead with a 30 foot eagle putt from the fringe of the seventh green on the third day of the Omega European Masters in Switzerland.
In what was already the 23rd change at the top of the leaderboard during the round, McIlroy became the first to reach 12 under par just after World Number Two Lee Westwood had joined the leaders with a 20 footer for his third successive birdie on the short eighth.
McIlroy, Northern Ireland's US Open Champion, had been part of a four-way tie overnight with Simon Dyson, Jamie Donaldson and Gary Boyd.
Welshman Donaldson and Englishman Boyd were still going well at ten under, but Irish Open winner Dyson bogeyed the short third and at seven under after six had fallen all the way to 16th place.
Things were so congested that 16 of the field were separated by only one stroke at one point and an even more amazing 13 different players had grabbed at least a share of top spot on the day.
England’s Nick Dougherty, who after starting with a pacesetting 63 had made his first halfway cut in 22 events going back to last November, resumed one behind and birdied the long first, but by following it with five pars in a row slipped to joint 12th.
While relieved to be earning his first cheque of the season the 29 year old needed a big finish to reignite his hopes of keeping his European Tour card at the end of the season.
Westwood made it four birdies in a row with a ten foot putt on the ninth and so turned in 31, one behind McIlroy.
Donaldson joined Westwood on 11 under, but then three-putted the ninth for a bogey six and slipped back alongside last week's winner Thomas Björn, Boyd, Danny Willett and World Number Five Martin Kaymer.
Westwood became joint-leader again with a two-putt birdie at the long 14th and McIlroy did well to stay alongside him, getting up and down from a bunker on the 13th.
They were a shot in front of Dane Søren Hansen, who came into the picture with an 18 foot eagle at the 15th.
The chances of a last-day showdown between Westwood and McIlroy increased when the former made a great up and down over a bunker to birdie the 15th and the latter chipped to six feet on the 14th.
At 13 under they were two clear of Donaldson, Hansen and his fellow Dane Søren Kjeldsen.
McIlroy went one ahead again with a two-putt birdie at the 15th, but then three-putted the next and bogeyed the 17th as well after going over the green from a fairway bunker.
Donaldson, meanwhile, had a hat-trick of birdies from the 13th and joined Westwood - round in a best-of-the-day 64 - on 13 under, one in front of McIlroy.
