Twenty players were within four shots of the lead midway through the final round of the Omega Dubai Desert Classic on Sunday.
Defending champion Stephen Gallacher began the day with a two-shot lead but bogeyed the first two holes after wayward drives and dropped further shots on the sixth and eighth.
That meant playing partner Rory McIlroy’s run of six straight pars was enough to inherit the lead, but the former world number one then promptly found the water with his tee shot on the par-three seventh.
A brilliant third shot from the drop zone to three feet meant McIlroy escaped with a bogey, but meant American Brooks Koepka took over at the top of the crowded leaderboard by chipping in for a birdie from the back of the eighth green.
At 14 under, Koepka – who won three times on the Challenge Tour last season to gain instant promotion to the European Tour – led by one from McIlroy, Steve Webster and Finland’s Mikko Ilonen, who had set the clubhouse target after a 64 which featured two eagles, five birdies and one bogey.
Gallacher was two shots off the pace on 12 under and in need of a similar finish that he produced in his third round of 63, where he covered the back nine in just 28 shots.
Koepka squandered a great chance to double his lead on the 10th, missing from three feet after an excellent bunker shot, and then bogeyed the 11th to drop back into a tie for the lead with Ilonen on 13 under.
McIlroy was a shot behind after making a complete mess of the 10th, going from one waste area to another and then into a bunker, while Gallacher was also only one off the lead despite being four over par for the day.