O Brother, who would have guessed this pairing?

Alison KRAUSS must feel as if she’s dreaming. Across the crowded green room at the NBC-TV studios early on a recent morning, a walking hot dog and a 6-foot-tall ketchup bottle are talking to Popeye and Olive Oyl. Then Hugh Hefner and a Playboy bunny come through a door.

Blinking, Krauss heads to the coffee urn. She’s been up since 3:30 a.m., she says, to make sure there’s plenty of time to do hair and makeup for her appearance on the “Today” show with her celebrated singing partner of the moment, Robert Plant.

“If they can’t do her in three hours, they might as well give up,” she says, putting herself in the third person and laughing at her joke.

Ungodly hours, by musicians’ standards anyway, are part of the bargain for the folk-country star and the British rocker as they do their bit to promote their collaboration, “Raising Sand,” which to their surprise is turning out to be one of the most anticipated albums of the year.

After doing interviews and taping a performance for the CMT cable channel’s “Crossroads” show in Krauss’ hometown of Nashville, they arrived here and went straight to a reception in their honor at an elegant tavern at Grand Central Terminal, then spent the next day visiting radio stations.

From New York they’re off to England for another round, and after Plant’s old band Led Zeppelin does its reunion show in December, the duo will start making plans for a U.S. concert tour.

Not many people were expecting this kind of attention for a project that began as an experiment with no clear aims -- least of all Massachusetts-based Rounder Records, the venerable roots-folk label that’s fostered Krauss’ career and now finds itself with a rock icon on its hands, and all that goes with it.

“It’s the most expensive record we’ve ever put out,” says Rounder President John Virant, standing at the bar during the reception, which figures to add a bit to the tab. “A lot of it was the travel for all the musicians -- Robert came over from England a couple of times. I remember getting an AmEx statement with $45,000 for airfare. . . . But when you’re working with people like this, you can’t run around crying that you’re a poor little indie.”

Virant is smiling as he says this. He figures it’s money well spent, and sure enough, when the numbers come in a week later, “Raising Sand” has entered the national sales chart at No. 2, selling 112,000 copies during its first week -- the highest in Rounder’s history. With the singers’ combined pedigrees and the critical acclaim it’s gathered and the spring tour to keep it fresh, the album could enjoy a long shelf life and be a factor in the 2009 Grammys.

T Bone Burnett, who produced the album, knows all about that. He assembled the soundtrack for “O Brother, Where Art Thou?,” the surprise album-of-the-year winner in 2002, which is when he first worked with Krauss.

“She is a profound artist and it’s sort of easy to overlook that somehow, because she’s so good at what she does,” Burnett says. “But the reality is she has very deep notions about music and art. She doesn’t wear them on her sleeve, but she may be the most uncompromising person I’ve ever met in my life.

“And Robert. . . . In a way Robert’s sort of the fulfillment of this threat that Elvis Presley made.”

Bluegrass meets rock

The hot dog, the ketchup bottle and company have finished their “Today” segment (it’s about Halloween costumes), and now Krauss and Plant are in a corner of the small studio in Rockefeller Center singing “Gone Gone Gone (Done Moved On),” a bouncy, driving Everly Brothers song from “Raising Sand.”

The 36-year-old bluegrass princess and the erstwhile rock god, 59, blend their contrasting voices with the assurance and rapport they’ve developed over the course of their collaboration. That began when Plant invited Krauss to sing with him at a tribute to folk/blues giant Leadbelly at the Rock and Roll Hall of Fame in 2004, and flowered in the “Raising Sand” sessions last year in Nashville and Los Angeles.

After the final chorus and a “Well well!” yelp from Plant, the singers stand back and watch as their band builds the intensity. Jay Bellerose’s drums dance lightly around the contours, while Burnett, Buddy Miller and Mark Ribot -- a summit meeting of premier roots-conscious, cutting-edge guitarists -- put on a show of their own.

Plant, who heard his share of guitar virtuosity in 1960s England and with Led Zeppelin, is still marveling at the display a few minutes later.

“When you see that there, Buddy Miller and Marc Ribot and T Bone playing,” he says, shaking his head. “It’s such a minimalistic piece of music, and yet with all that prowess and skill and musicality it becomes even more minimal.

“And then of course Ribot plays a solo that we haven’t heard before and didn’t know was going to happen, which makes it really good.”

A natural chemistry

He and Krauss laugh, something they do often as they sit in a dressing room after the show. Weathered in visage but still robust in manner, Plant is gracious and self-effacing, a sort of wry, experienced Michael Caine figure to the younger Krauss.

Krauss got her doses of Led Zeppelin from her older brother, but her interest in Plant traces more to his first solo hit, 1983’s moody, Spanish-inflected “Big Log.”

“I appreciate him as an ever-changing artist, where he’s going and what he’s done through his career,” she says. “Just how things kept evolving into something that you have no idea where it’s going to be in five years. I love that about a person.”

Not that she is some awe-struck protege. Krauss, who has won 20 Grammys and sold 8.6 million albums on her own and with her band Union Station, was the one who insisted on their album’s dark mood, and she pretty much owns the world of folk/country/Americana that Plant was stepping into, with some apprehension.

“Well, Alison’s very patient, but because she’s born to it and I wasn’t, we didn’t really know,” says Plant. “I know that there was a bit of consternation. I could feel the Americans twitching.”

Not at all, says Burnett, who not only assembled the musicians, shaped the sound and directed the sessions, but also selected the songs that formed the album’s backbone.

“People talk about what a strange pairing it is, but from the moment I heard it I thought, ‘Oh, that’s exactly right.’ ” says the Los Angeles-based Burnett, sitting in his suite at a Central Park South hotel the day before the “Today” performance. “They both have that same otherworldliness that I strive for, in my life and in the world of sound that I surround myself with.”

Burnett started gathering material and got help from his friend Elvis Costello, who suggested Tom Waits and Kathleen Brennan’s “Trampled Rose,” which is on the album, and PJ Harvey’s “Pocket Knife,” which was recorded but was left off because Krauss wasn’t satisfied with her performance.

Burnett also furnished two songs by the late Gene Clark (of the Byrds), including the majestically intimate dirge “Polly Come Home,” and Plant brought in five songs, including “Gone Gone Gone” and another one cut by the Everlys, Mel Tillis’ “Stick With Me Baby,” as well as the British beat-era staple “Fortune Teller” and the playful “Rich Woman,” originally recorded by New Orleans R&B; singer Lil’ Millet.

They finally had their set, a diverse collection of blues, folk-rock, cabaret, country, rockabilly, Appalachian and R&B;, unified by a haunting sound quality and a thread of sorrow in the words. Even the upbeat Everlys tune carries a lyric about desertion and betrayal

Their singing assignments range from solo showcases -- Krauss’ eerie take on “Trampled Rose” and Plant’s absorbing encounter with West Texas existentialism in Townes Van Zandt’s “Nothing” -- to twined harmonies, such as the Carter Family-style finale “Your Long Journey,” written by Don Watson and his wife, Rosa Lee.

“That’s the beautiful thing,” Burnett says, “when you just lose track of who’s singing where.”

Burnett framed those vocals in a sound that honors tradition but refracts it through his own restless vision, which currently owes a lot to contemporary classical composer John Adams.

“He’ll take two tones and collide them, and then more tones and more tones, so these overtone rhythms get set up,” Burnett explains. “You’re never dealing with a point.

“What I was striving to do was not having it on a grid, not having a specific beat that happened on a pixel. A beat isn’t something that happens like that” -- he claps his hands sharply. “A beat is something that unfolds as long as you can make it. And then you put another beat behind that and all of those tones start colliding and it turns into a whole different way of hearing.”

Burnett mentions the work of John Sharpley, a Singapore-based American who sometimes performs his piano pieces in natural caverns. .

“You’re overwhelmed by the amount of information. There’s no possible way to receive it consciously, it just has to enter you. So that’s the sound.”

Smokin’ and smolderin’

“He’s a swashbuckling guy. I knew that he was a renegade,” Plant says of Burnett. “But also I found out that he’s just got a spectacularly successful way of keeping it interesting and constantly illuminating more within a particular song.

“We’d finish a song in a particular fashion one night and then come back the next morning and he’d put on some tremolo guitar . . . and it had become so smoky. And that immediately made me feel, ‘Wow, this is what I want. This is Lil’ Millet, this is New Orleans 1956.’ And that was Alison’s decree. We got to make it smolder and make it some shady-sounding collection of songs.”

“It needed to be dark, lyrically heavy,” Krauss explains. “There’s so much life and experience that his voice brings out, there’s a lot of mystery to it, and with mine together, that creates some kind of story, and I don’t think it creates an ‘up’ story. I think it creates a lot of wonder and it creates sadness.

“That’s the emotion I feel when I hear us sing together,” she says. “It’s something that has a past, and it won’t be as effective with a different kind of environment. . . . A smoky, heavier environment tells a much deeper story. Not only because of the lyrics, but the sound of our voices will tell a very different story.”

Krauss and Plant have to go pose for photos now, and they have a few more promotional duties in New York before they fly to England to spread the word in Plant’s homeland, where at least one fan is looking forward to their arrival.

“My sister, who normally thinks that my music -- well, she thinks that I should be sectioned, taken off somewhere and strapped down -- she’s texting me, ‘It’s so beautiful, I can’t wait to meet Alison, she’s made you sing properly.’

“It’s true, that’s what a lot of people say,” Plant says. “The women at the kitchen sink in England have been waiting for me to do something since ‘Big Log.’ ”

richard.cromelin@latimes.com

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Gonzo combos

Album producer T Bone Burnett is one of the few who hasn’t used the word “unlikely” to describe the Plant-Krauss pairing. Here are a dozen other surprising collaborations, past and present, that we humbly nominate as Pop’s Oddest Couples:

*--* 12. Mark Knopfler and Emmylou Harris

11. Emmylou Harris and Bright Eyes

10. Jack White and Loretta Lynn

9. Burt Bacharach and Elvis Costello

8. Elvis Costello and Anne Sofie von Otter

7. Phil Spector and the Ramones

6. Lee Hazlewood and Nancy Sinatra

5. Sonic Youth and Chuck D

4. Joni Mitchell and Charles Mingus

3. The Mothers of Invention and the Los Angeles Philharmonic

2. Pat Boone and James Brown *--*

And the No. 1 “Say what?” pop pairing in history:

1. David Bowie and Bing Crosby