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," hi

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 Oct. 23 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," the former Led Zeppelin singer says via phone from his home in England.

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. The sound is dark and groove-oriented, with rich guitar work by Marc Ribot and Norman Blake.

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."

The two singers met and performed together for the first time in 2004 at a Leadbelly tribute at Cleveland's Rock and Roll Hall of Fame. Inspired by an "inquisitivity about what it would sound like to blend two radically different vocal styles together," Plant suggested they collaborate. "I had no preconceived ideas about what this record would be," Krauss says with a laugh. She suggested Burnett as a producer. "Robert was like, 'Yeah!,' " she recalls.

Krauss says "Raising Sand" started taking shape once Burnett began sending material to her and Plant for their consideration. "I remember thinking, 'Oh, my goodness, look what we have here,' " she says. ("I came up with some ideas but Alison said I needed to be darker than that," Plant admits.)

Burnett says his criteria for selecting songs was simple: "I wanted to find stuff I could imagine them killing." The producer says they steered clear of chestnuts, preferring to tackle lesser-known songs that forced Plant and Krauss to venture beyond their comfort zones. "Robert's interest is primarily in Delta blues, and Alison's is mostly Appalachian music. So my tendency was to give him the Appalachian stuff and her the Delta blues. By the end of the record, Robert's doing a Doc Watson tune, 'Year Long Journey.' He's never gotten close to that kind of country music before."

Rounder executive VP Sheri Sands says, "Both of these artists have always shown a willingness to expand the boundaries of what they do. With this album, they've created something really special that's really hard to define." That challenge doesn't worry Sands from a marketing standpoint, though. "The response has been positive from every account: mass merchants, indies, chains. I don't remember the last time there was this much enthusiasm across the board for a project," she says.

The first phase of Rounder's radio plan is to launch the record at triple-A, noncommercial, college, rock and NPR stations. "Once we go into those areas, we'll look to expand, whether it be country or hot AC," she says. "We're looking at all possibilities."

Rounder plans to produce a video from the record, possibly for the song "Gone, Gone, Gone." "We're also talking about filming an episode of CMT's 'Crossroads' in October," she adds. CMT senior VP of music strategy Jay Frank says, "Our audience is looking forward to seeing what this collaboration holds, and we're enthusiastically awaiting the first video they will create."

Plant, Krauss and Burnett plan to support "Raising Sand" on the road, perhaps with a tour next summer. (Plant declined to answer questions about potential further activity in the Zeppelin camp.) "We'll definitely be doing stuff not on the record," Burnett says. "There's too many fun possibilities not to." 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?"