Defending champion Stephen Gallacher played the back nine in 28 to accelerate into the third-round lead at the Dubai Desert Classic.
The Scot's nine-under 63 took him to 16-under-par overall and a two-shot advantage over world No 6 Rory McIlroy, who managed a 69.
Gallacher played his last 10 holes in 10 under, although there was little sign of what was to come when - four behind overnight leader McIlroy - he opened with seven pars and then bogeyed the eighth.
That left him seven back, but the turning point came at the par-four ninth where Gallacher picked up a shot thanks to a superb approach.
He then proceeded to reel off three more birdies to start his inward half, eagled at the par-five 13th, parred the next and finished off with another four-birdie run.
Gallacher told Sky Sports: "It was a bit of a struggle to start with, especially the first three holes when I failed to find the fairway.
"Then I hit it stiff at nine and, from then on, kept hitting it close - and if I hit it to 30 feet I holed it.
"It was just one of those days where I didn't feel quite right early on. I missed from about six feet at seven, hit a poor putt at eight and thought: 'oh no, here we go...'
"(But) If you stay patient, focused and keep your head then it's amazing what this game throws up."
Gallacher's victory last year was the second win of a professional career that started in 1995 and he is aiming to draw on that experience on Sunday to become the first man to successfully defend the title in the 25th edition of the event.
"What I found last year was it's easier leading than chasing (on this course)," he said.
"There is a lot of golf left to go but I'll certainly be giving it my best shot."
McIlroy, whose maiden career title came five years ago at this tournament, made an adventurous bogey-birdie-eagle start to his third round.
The Northern Irishman had another bogey at the sixth but responded with a solid remainder to the day, mixing 10 pars with birdies at the 10th and 17th.
He sits at 14-under-par, two better off than his playing partner Brooks Koepka (70) and Dane Thorbjorn Olesen (65).
Englishman Steve Webster made a big move with nine birdies and an eagle in his 64. Webster is joined at 11 under by countryman Robert Rock and Italian Edoardo Molinari, who both signed for 68s.
World No 1 Tiger Woods shot 70 to occupy a share of 37th place on five under.