The Englishman made six birdies to take his total to 15-under 201. England's Ross McGowan was second after also shooting a 66.
Westwood has also opened up a five-shot advantage over Rory McIlroy of Northern Ireland, his only remaining rival for the Race to Dubai. Should he win both titles, Westwood will receive $2.75 million and be Europe's No. 1 player for the first time since 2000.