Starting three shots behind, Westwood now leads McIlroy by two and Bjorn by three, while outsiders Marcel Siem, Stephen Gallacher and Rafael Cabrera-Bello are joint-second on 14 under.     

Westwood, 38, had sunk birdies in the final three holes on Friday and the Englishman took his blistering form into the third round, picking up shots in three of the first four holes to move to 13 under.     

The world number three’s charge then stalled as a birdie on the seventh sandwiched two bogeys, reaching the turn at 12 under.     

The back nine of the Majlis course is more forgiving, with three par-fives and two short par-fours and Westwood made birdies at the 10th, 12th and 13th before shooting par for the remainder.     

Westwood’s charge inspired his playing partners, Gallacher of Britain and Germany’s Siem, who each shot 68 to belie their lowly world rankings of 148 and 223 respectively.               

    DESERT TOIL     

Northern Ireland’s McIlroy and Dane Bjorn started the day 13 under after rattling in a succession of birdies in near-perfect conditions on the first two rounds.      

Saturday was a different story, however, as offshore gusts buffeted the fairways and temperatures topped 30 degrees Celsius, making it tough for the leading pair as they teed off under the midday sun.      

By the turn, Bjorn, 40, was one under for the round and one ahead of Westwood, having squandered a two-foot birdie chance on the ninth green, while McIlroy was on par.     

It could have been worse for the 22-year-old Ulsterman.

Normally so strong on his long game, the world number two missed the fairway from the tee on four of the opening nine holes, most calamitously on the seventh when his drive cleared the lake but then rolled back into the water for a penalty shot.     

He made partial amends, staying calm to sink a 20-foot putt down the slope to escape with a bogey.     

But Bjorn, who himself had bogeyed the fifth, took full advantage, tapping in a five-foot birdie putt for a two-shot swing to reclaim the lead.     

McIlroy’s solitary birdie of the opening nine came on the second hole, sinking a 10-foot putt on the short par four and all the while Westwood was gaining ground.     

Bjorn’s miss on the ninth jolted the Dane, who shot bogeys on three of the closing four holes, finding the water on the last, to end three shots off Westwood.      

McIlroy fared little better and was the only player in the top eight to fail to birdie the par-five 10th, missing the fairway with his tee shot and then skewing into the bunker to eventually putt for a bogey.      

He then picked up birdies in two of the next three holes, but the demons returned on the 14th and 16th as he shot four bogeys in 10 holes.