AceShowbiz -

John Mayer and Sarah Silverman, they are among numbers of celebrities recruited to pose for Gap's fall ad campaign, "Classics Redefined," captured by acclaimed photographer Annie Leibovitz.

The singer and comedian are joining the likes of Forest Whitaker, Liev Schreiber, Lucy Liu, Regina King, Selma Blair and Ken Watanabe, all of whom pose for the campaign to be featured across Canada online and outdoors as well as in the September issues of magazines, like Elle Canada, Fashion, Flare and Wish among others.

"Fashion portraiture is a subject near and dear to Gap. Our advertising has always put the individual ahead of the clothes," founder Don Fisher said in a statement. "Whether it's a celebrity, a writer, a performing artist or a model, the person is always the art, the clothes the frame that sets them off. A photo is a way to capture that moment so it doesn't pass. And a compelling portrait is a way to make sure it lives on forever."

"Classics Redefined" includes such items, as sweater vest, tailored white shirt and haberdashery shirt for men and a little black sweater dress, wide-leg trouser and deep V sweater for women.

Some other notable names featured in the ad including director/producer Davis Guggenheim, choreographer/director Twyla Tharp, designer Marcel Wanders and Japanese pop stars Puffy AmiYumi.

Click here to see photos of the celebs posing for the ad and here to see details of the line complete with the price.