Thorbjorn Olesen shot a course-record 62 to take a commanding six-shot lead after the second round of the Turkish Airlines Open on Friday.
Adrian Otaegui had earlier shot a 63, but Olesen went one better to enter the weekend at 15-under 127 and open up the largest 36-hole lead of the European Tour season.
Otaegui and Thongchai Jaidee (66) were tied at 9-under, one stroke ahead of Joakim Lagergren (64), David Horsey (67), Matteo Manassero (68) and Li Haotong (68).
The 26-year-old Olesen had made only four of his last 13 cuts but he was in good form at Regnum Carya Golf and Spa Resort, making an eagle and eight birdies.
On the par-4 17th, Olesen drove into the rough but then curled his second shot around some trees and into the center of the green to set up a successful birdie putt.
All three of Olesen's European Tour titles have come when he has held the 54-hole lead.
"I feel like I've been up in contention in a lot of big events," the Dane said. "I feel pretty comfortable. There is still 36 holes to go, so that's a lot of golf to be played, but I have to keep being aggressive out there. That's the only way I can win."
It was a difficult day for Masters champion Danny Willett, who needs a top-five finish to overtake Henrik Stenson and return to the top of the Race to Dubai standings.
Willett (74) dropped to 1-over and was in a tie for 58th place.