Justin Timberlake on his new clothing line -- The pop star talks about the inspiration for his new fashion collection

Justin Timberlake’s uniform of choice circa 1999 was a tight muscle tee and a matching white-boy ‘fro. Fortunately, time — and taste — marches on: The ringlets were shorn and the tanks were booted for designer blazers. Confirming his fashion maturity, Timberlake, 24, recently launched a clothing line, William Rast, with partner Trace Ayala, 25 (the label is a combination of their grandfathers’ names). Timberlake says the line is a natural progression. ”Trace has always been involved in fashion and design, so we decided to create a collection.”

More Von Dutch than von Furstenberg, William Rast hit upscale department stores like Bloomingdale’s earlier this month. And hopefully it will fare better than the label of former bandmate Chris Kirkpatrick. (Anyone remember his label, FuMan Skeeto? Anyone?) Ayala says their collection will eventually grow to include dressier items as well as its simple debut selection of vintage-looking tees and high-end denim, which he calls ”Southern country-club couture,” a shout-out to their Tennessee roots.

The pair had no comment on whether famous g-friends Cameron Diaz and Elisha Cuthbert (Ayala’s fiancée) had input. But Timberlake was loud and clear on one point: Unlike celeb lines where the stars are involved in name only, he’s contributing a lot more than marquee value. ”We’re both involved in everything, from fabric to style to the most minute details such as button design and pocket placement,” he says. ”We do everything but the actual sewing.” Too bad: The idea of Timberlake fumbling with a needle and thread is kinda cute.