LOS ANGELES, California (CNN) -- Robert Plant and Alison Krauss. Once upon a time, the iconic lead singer of Led Zeppelin and the golden girl of bluegrass would never have been mentioned in the same sentence.

But since they won five Grammy awards -- including album of the year for their surprising collaboration, "Raising Sand" -- their names have been inextricably linked: RobertPlantandAlisonKrauss.

If they were 20 years old and ran in Hollywood circles, tabloids might be calling them Robekrauss or Aliplant.

Plant, however, is 60 -- in fantastic shape, and with a full head of the golden ringlets that became his trademark during the 1970s.

At 37, Krauss is elegant and ethereal. And while both are dead serious when talking about their craft, the rest of the time, they're like two silly junior high kids -- he, the charming prankster with a secret crush, and she, the beautiful prom queen who pretends not to be amused.

Clearly, they're both having the time of their lives, and are excited about their current musical journey -- which pushes each out of their respective comfort zones and into new territory. Now, he's a little bit country and she's a little bit rock 'n' roll.

I compliment Krauss on her hair as a stylist touches her up. "It's not mine," she whispers.

Two feet away, Plant clears his throat loudly and points to his own golden locks. "Why, your hair looks lovely, too, Robert," I say.

"Well, you know who I am," he replies.

We are in Coldplay's vacated dressing room, two nights before Plant and Krauss swept the evening at the 51st annual Grammy Awards. This is an excerpt from our conversation in the basement of Staples Center in Los Angeles the night of their rehearsal.

CNN: First of all, this is the screwiest collaboration I had ever heard of. How did this happen?

Robert Plant: It's just sheer luck, really. I never sang with anybody before, you know -- only once ever in my life, on "Led Zep IV" with Sandy Denny [the late English folk singer, in 1971]. So this is a whole new thing. I've also been coming to the United States for 40 years -- you wouldn't believe it looking at me -- and I've never worked with Americans! This is all brand new for me.

Alison Krauss: Were we both nervous? We both were. We thought, "What are we going to do in there?" We went into the studio originally saying, "We'll give it three days and see what it's like."

Plant: Alison's reputation is 24 karat, and I'm an old rock 'n' roll singer. Even the band was kind of going, "Oh wow, how is this going to work?" It was great when we kicked in together, and I could just feel the room -- I don't want to say it, but the room lifted!

CNN: Musically, you're polar opposites. How did you blend your different perspectives?

Plant: As we got started, it was Alison's world. She knew how she wanted to proceed, and we exchanged a lot of ideas musically. And then we both agreed that because we both produced records ourselves, that we needed an intermediary to guide -- somebody to separate us, or to make the journey more clear. And Alison knew T Bone Burnett from "O Brother, Where Art Thou," and he kindly enlisted for the gig, and he brought a lot of great songs to the show.

CNN: You challenged one another to sing in different ways than you're used to.

Plant: When she goes up for these wailing notes on stage, that's where I want her to go with this new project -- occasionally visit these places where she lets rip, and just lets it really come out.

Krauss (melodramatically): It's just reckless abandon! It's just crazy!

Plant: I don't know why I'm being so serious. She just kicks ass and nobody knew it!

CNN: Now this is all making sense. With Alison, it's letting go, and with you, Robert, it's kind of containing things.

Plant: I'm being bullied, basically. Pushed around.

CNN: But you like it. Admit it, you love it.

Plant: Oh, I do! I haven't even gotten off to being bullied enough yet.

CNN: Did you have this much fun working with Zeppelin?

Plant: I can't remember. Honestly, I haven't got a clue. I was a totally different guy then. It was 28 years ago. I didn't look as good as I do now, and I didn't share the couch with another Leo.

CNN: Alison, did you listen to Led Zeppelin growing up?

Krauss: We all have, yeah. (Plant is shaking his head and mouthing the word "No.") My brother was and is such a huge fan of the band, and I remember growing up and he would be in his bedroom yelling about the records and how great they were.

CNN: Robert, were you familiar with Alison's work?

Plant: Yeah, to some degree, but not as intensely as I became. And also, I didn't understand the history of where Alison's from [bluegrass], and has been since she was a child. In fact, both of us can sit there talking about music, and neither of us can recognize the artists we're referring to. It's amazing. I mean, all the rock 'n' roll, and black Mississippi and Chicago stuff that I go raving on about, she's going, "Hmm."

Krauss: I didn't grow up on that, yeah.

CNN: Has he made you listen to his music collection?

Plant: We share.

Krauss: I bring bluegrass. It's the same people. Same blue-collar people. Just one was south of the Delta, and one was Virginia and Tennessee and North Carolina. So we've got lots in common -- but it's the presentation and the whole musicality of it that's different.

CNN: Your collaboration has worked out so well that you're back in the studio in Nashville, working on a second album together.

Plant: We'd like to keep it going.

CNN: Do you think there's going to be an album No. 3, and an album No. 4?

Plant: I'd have to move to Nashville, wouldn't I?

CNN: Or she moves to England.

Plant (to Krauss): Could you stand the climate?

Krauss: I'll get a heating pad.

Plant: And a season ticket for Wolverhampton Wanderers football club. That's important.

CNN: You gained a lot of fans with this project, but there are those Led Zeppelin diehards who've been holding their breath for a reunion tour -- especially since you reunited for the Ahmet Ertegun tribute concert at Wembley in 2007.

Plant: Well, we had a really good night, and we had great rehearsals, and it was very emotional -- and if you like, quite elevating. But it was the right thing to do to do it that way. There's no bandwagon. We've already been around the world, and did what we did when we were young men.

CNN: That sounds like a man who's looking forward, and not back.

Plant: Only last week, I was being grilled again by Alison to get into shape and get it right. And that's fantastic! I really want that. I don't want to go around, everybody thinking, "That's what he did." Because this is what I do, and every day, it should be more interesting.

CNN: And in the meantime, you've been recognized by the Grammys.

Plant: We've already won by doing this. We've brought our gifts, and we've shared them, and the whole surrounding musically is so beautiful, that that's our reward. The fact that it worked. The fact that it wasn't some embarrassing moment of two people trying something out, and saying goodbye, and then meeting at a party years later and saying, "Oh, Christ, there's Alison Krauss! Oh, no!"