Danny Willett kept hold of his one-shot overnight lead as the final round of the Omega Dubai Desert Classic reached its midway stage.
The Englishman picked up a single shot on the front nine to sit 17 under, a stroke clear of countryman Andy Sullivan as an ominous chasing pack took advantage of the best scoring conditions of the week.
Defending champion Rory McIlroy fired a brilliant 65 but that was only enough to get the World Number Two to 15 under and he looked highly likely to relinquish his crown.
Byeong-hun An was also at 15 under after 15 holes of his round with Rafa Cabrera-Bello level par for the day at the turn.
Willett made a great par at the first after finding a bunker but could not repeat the trick from a waste area on the next and, after Sullivan also made par from sand on the first, the man from Nuneaton birdied the second.
Another birdie followed on the fourth and an excellent par save at the fifth kept him at 16 under, where he was joined by Willett who put his tee shot on the fourth inside eight feet.
Willett followed that up with another gain on the fifth and Sullivan dropped his first shot in 59 holes on the sixth to make it a two-shot lead.
Another birdie from Willett on the seventh gave him a comfortable cushion but Sullivan birdied the ninth and when Willett dropped a shot on the same hole, the gap was down to one.
McIlroy took his record on the back nine this week to 15 under par in his round while a run of four birdies from the tenth helped catapult An up the leaderboard.
Cabrera-Bello, the 2012 champion here, had a bogey on the sixth and a birdie on the eighth to sit a shot clear of fellow Spaniards Alejandro Cañizares and Alvaro Quiros, and World Number Six Henrik Stenson.
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