Swede Peter Hanson equalled the course record to storm to the lead at the Dubai World Championship with an eight-under 64.
Rory McIlroy staged a late charge with six birdies on the back nine as world No.1 Luke Donald's round fell apart at the seams.
The US Open champion, who, should he win the tournament, needs Donald to finish outside the top nine to win the Race to Dubai title and take out the European Tour's order of merit, staged an amazing recovery after an indifferent start to shoot a 66 for outright third.
Donald, meanwhile, was three-under after the front nine and led his chief rival, before three bogeys on the back nine saw his round unravel and peter out to an even-par 72.
Like McIlroy, leader Hanson hit six birdies on the back nine to lead Scotland's Paul Lawrie by a stroke after the first round and admitted everything went right.
"This was the best round that I ever played. It was just one of those days that everything seemed to go right," Hanson said.
The 34-year-old finished third behind McIlroy in Hong Kong last weekend but is yet to lift his maiden trophy.
"It's quite a demanding course and the wind picked up a little bit over the back nine," Hanson said.
"I'm very, very happy with the way I struck the ball - and I rolled a few putts in."
Spaniard Sergio Garcia shot a 67 for outright fourth, while countryman Alvaro Quiros and England duo Ross Fisher and Robert Rock share fifth place at four-under.
However, much of the focus remains on the duel between Donald and McIlroy.
After the first nine it looked as if Donald was in control with McIlroy seven shots off the leader and three behind the world No.1.
The Northern Irishman lost a ball and double-bogeyed the par-five second, but his resurgence paired with Donald's string of uncharacteristic errors has left the door ajar.
A top-nine finish will ensure he completes an unprecedented money list double but there is still work to do with the Englishman languishing in a tie for 26th.
Inaugural Dubai champion Lee Westwood could manage only a one-over 73.