Robert Plant shocked many by agreeing to play a one-off show with Led Zeppelin in November in London. But he isn't particularly concerned that his fans might be taken by surprise by "Raising Sand," his new collaboration with bluegrass bigwig Alison Krauss, due this week from Rounder. "If people have enjoyed my career, then they'll know that not a single record that I've made since 1968 has had anything to do with the one before," he says.

Instead, what vexes Plant is the idea that "Raising Sand" will be the victim of the D-word. "The worst thing in the world is to say, 'Hey, these guys are making a duet album,'" he says. "A duet is normally something that's kind of sugarcoated and has a kind of saccharine quality to it. This is nothing like that. These are visitations, really, where Alison will bolster me or I'll augment her. [Making this album] was like opening the bottle and out pops the genie that nobody expected."

If that sounds like big talk, the album's big sound backs Plant up. Produced by T-Bone Burnett, the 13-track collection finds the two singers applying their considerable interpretative skills to a shrewdly selected set of American roots-music gems, including Gene Clark's "Polly," the Everly Brothers' "Gone, Gone, Gone" and "Trampled Rose" by Tom Waits and Kathleen Brennan.

As Plant suggests, he and Krauss don't simply harmonize; rather, their vocals engage in a loose back-and-forth that creates what Plant calls "a sort of musical landscape." Plant adds that he absolutely intends to make another record with Krauss: "Listen to how good it is. You wouldn't want to say goodbye to that quickly, would you?"