Trying not just to win The European Tour's flagship event, but also to deny Luke Donald his World Number One spot, Westwood hit back from a bogey at the third with three birdies in the next five.
For the second day running Donald teed off as joint leader and made a bad start, bogeying the first two holes on this occasion.
But this time he came back with a birdie at the long fourth and by following that with five pars he was one behind, along with compatriot Simon Dyson.
Joint overnight leader Matteo Manassero was only two back in fourth spot, while Colin Montgomerie's 68 lifted him to joint sixth and in with a great chance of his first top-ten finish for almost three years.
Donald drew level with a six footer at the short tenth, only for Westwood to grab a rare birdie on the 480 yard 12th.
He was six under, Donald five under and then there was a two shot gap to Manassero and Dyson, who bogeyed the 13th.
Westwood pulled his drive down the 15th into the crowd, but then produced a brilliant approach from the rough that curled round to four feet.
When the birdie putt went in he led by two at seven under, leaving Donald needing something special.
Westwood gave Donald hope again by driving onto the edge of a bunker at the 383 yard 16th and bogeying to slip back to six under and only one ahead, with Dyson two back after missing chances at the 16th and 17th.
And then the game's top two were back level when Donald fired in his approach to within 18 inches of the flag at the 16th.
He was in the same position he was last year - and on that occasion he ran up a seven at the long 17th and lost by one.