By Matt Smith
The world number three started the day at 15 under, one shot clear of playing partners Marcel Siem and Stephen Gallacher, while U.S. Open champion Rory McIlroy, who had been leading at the halfway stage, started two off the pace.
Both Westwood and McIlroy had wanted tougher conditions to make the Majlis course bare its teeth following a birdie bonanza on a tranquil opening two days and the British duo got their wish on the final round as swirling gusts of up to 25 miles per hour buffeted the fairways.
The short par-four second hole provides one of the best chances for players to pick up shots on a tough front nine and
Westwood's blistering tee shot ended 35 feet from the pin but short of the green.
He opted to putt rather than chip, rolling the ball in for an eagle to move 17 under for a two shot lead, while Gallacher dispatched a birdie to move back to 14 under and Siem also gained a shot.
Westwood made his first mistake on the fifth tee, fading his drive into the rough to the right of the fairway and from there he again found the rough, this time five yards from the green.
His subsequent chip ended seven-feet from the hole for a tricky shot for par and he was found wanting, rolling his effort wide to eventually make a bogey and slip back to 16 under.
Siem landed his tee shot just off the green within nine feet of the flag on the tricky par-three seventh, made more treacherous by a gusting cross-wind across the lake, but the pony-tailed German fluffed his birdie chance and holed for par.
Westward was wayward, landing at the bottom of a steep bank of rough some way from the pin. He played a low chip that ended four feet away and holed on the next shot to escape with a par.
Gallacher missed a 16-foot putt, making bogey to slip back to 14 under, two off the pace.
Siem sunk a birdie on the eighth to join Westwood on 16 under, but his joy was short-lived as he then bogeyed the next hole to slip a shot behind.
McIlroy struggled, shooting a bogey on the first hole after skewing an 8-foot par shot wide and the Ulsterman then sunk a double bogey on the ninth to slip back to 10 under.
(Reporting by Matt Smith, editing by Alan Baldwin)