Luke Donald took control of the DP World Tour Championship in Dubai by going to the turn in 32 on Saturday - and had still to drop a stroke all week.
Birdies at the second, third, seventh and ninth lifted England's world number two to 15 under par in the European Tour's season-ending event.
He led by two from South African Louis Oosthuizen, while world number one Rory McIlroy was in a group three behind.
McIlroy and Scot Marc Warren shared the overnight pace with Donald, but they had early troubles.
The Northern Irish star put his opening drive into sand and bogeyed, then had to work hard for a par on the 583-yard next after pulling his tee shot into the bushes.
Warren, 189th in the world, did the same and after being forced to take a penalty drop - McIlroy was able to hack out - ran up a bogey six.
He was still searching for his first birdie of the day after nine holes, but McIlroy did at least come back with birdies on the third and short sixth.
Donald, trying to become the first player to win a tournament on the circuit without a bogey since Jesper Parnevik in 1995, sank 10-foot putts at the second and third, chipped close on the long seventh and then finished the outward half with his fourth birdie.
Former Open winner Oosthuizen moved into second place with a hat-trick of birdies from the seventh.
Earlier Indian Jeev Milkha Singh became the seventh player to have a course record 64, missing a 15-foot chance to set a new mark on the final green. The round lifted him from one over to seven under.