I TELL YOU, there's never a dull moment in this job. It's Sunday afternoon at Witnness, and in the past half-hour I've had to intervene to stop Ron Sexsmith peeing in a washbasin, been berated by Asian Dub Foundation for owning a Bernard Manning video, and seen Nicole Appleton getting seriously carnal with a tub of Haagen-Dazs. Now I'm positioned 10 feet away from Beck, as some VJ-type from MTV quizzes him about Winona Ryder. Despite Andy Cairns' protestations that she's here to see Therapy? - "You can't keep that girl out of the moshpit" - the backstage title tattle is that Ryder has flown in to spend some quality time with the singer, who's just split from his long-term girlfriend.

Seasoned pro that he is, the 30-year-old laughs off the inquiry, and starts talking instead about his Mississippi John Hurt fixation.

Looking effortlessly cool in a Black Sabbath Never Say Die t-shirt and designer shades, Beck is entertaining a few select media types prior to his Main Stage show, which turns out to be gobsmacking in its brilliance. I rarely get nervous before an interview, but there's such an air of big deal about the Californian that by the time we get to exchange manly handshakes, I'm twitchier than Woody Allen at a PTA meeting. My state of mind hasn't been helped by a press room conversation with a bloke from the BBC, who reckons that the boy Hansen ranks between Lou Reed and Van Morrison in the affability stakes. Not for the first time, I thank God that I left university with an H.Dip in Brown-Nosing, and tell Beck that he's got great taste in tops.

"Thanks," he beams. "It's a 1978 original, which by some freak of nature has withstood all the punishment I've given it. If an alien arrived on Earth and wanted to know what heavy metal is, you'd play them the first Black Sabbath album. I'm unusual in that it's the ballads, like 'Changes', that I get off on the most. Ozzy Osbourne has to be one of my top five favourite voices. I wouldn't bet money on him hitting a particular note, but soul and passion-wise, he's up there with the greats.

"I met him a couple of years ago at an awards show. The circumstances - as they normally are at those events - were kind of stressful, but he was everything I'd hoped he'd be. And more, actually. It's obvious from talking to him that he's crazy about his wife and kids. The reality and the public persona are never the same."

That's certainly the case with Beck, who's so scrupulously polite that I keep expecting him to try and sell me a copy of Watchtower. Having crossed "miserable git" off our list of character defects, how does he feel about the suggestion that he tends to overdo the enigma bit?

"Wow, I've never had that said to me before. There's a world of difference between trying to bestow enigmatic status on yourself, and not wanting to be in everybody's face all the time. I've never felt the need to saturate humanity with my presence. I've nothing against her personally, but America at the moment is in the grips of Britney fascism. You simply cannot get away from the girl, which may be working in her favour now, but will eventually lead to the country screaming 'no more!'

"I really, honestly, truly love just getting up and performing," he continues. "Sometimes I worry that I'm obsessed, but that and making records are part of my genetic make-up. It's the way I breathe and think and sleep."

Where does he stand on the teen pop issue?

"The beautiful thing would be if one of them evolved into The Beach Boys. I'd be the first to shake N'Sync's hands if they produced a modern Pet Sounds. Perhaps Britney Spears will develop into a Frances Gall. I'd rather fantasise about them coming out with a masterpiece than criticise them for their existing shortcomings."

While generally regarded as one of the most talented musicians of his generation, Beck's own take on his career is that he's a Johnny-come-lately who still has loads to prove.

"I was looking at a Japanese magazine that runs little photos of an artist's albums along with the stories, and I look at someone like Neil Young or David Bowie and there are 30 or 40 there, and it makes me realise that I'm still just beginning," he recently informed MTV Asia. "I'm at four albums which would put me at Ziggy Stardust or Aladdin Sane in terms of Bowie's albums. I'd like to think I'll have 30 or 40 someday, but who knows? Maybe there'll only be four or five, and you want to be proud of each one. You never know when you're going to go through that door."

Most musicians would've been delighted to top the American charts with only their third single, but for Beck it was a headfucking experience that still haunts him.

"I can remember the exact moment when I realised my life was about to change," he observes. "It was in August of 1993. I hadn't released an album yet, but 'Loser' was a hit on the radio, and I'd gone up to Seattle to record. I was on a bill with four other bands for a Sunday concert, and I spotted a girl in the audience who was about 14 years old and had my name written on her forehead in Magic Marker. It absolutely terrified me, and I don't know why. Maybe if I'd been a little older or was in a band with some friends, I would've enjoyed that moment, but for me, it all happened so fast and so awkwardly."

All of this, by the way, is said without any trace of self-pity. He may have had his difficulties dealing with fame, but Beck is well aware of the good things it's brought him. Such as getting to record a duet with another of his top five voices, Willie Nelson.

"If you'll allow me to steal a quote from Kerouac, Willie Nelson is completely beatific," he proffers. "He's one of that special breed of people whose presence enters the room before he does. I was terrified that I wouldn't be up to the task, but gentleman that he is, he put me at my ease and we had a wonderful time.

"You know how his voice is very understated? Well, when you're singing with him, he's as loud as shit. The resonance in his chest, and the way he projects, borders on the superhuman. He's 67 and still completely intact - unlike his guitar which has a hole in it from his thumb hitting off the wood. The solo he played, man, it destroyed me."

Who's the cooler OAP, him or Johnny Cash?

"That's a tough call. Let's just say that when I grow up, I'd be proud to be either one of them. It's the Johnny Cashes, Willie Nelsons and Boxcar Willies that make you think, yeah, I can keep doing this for the rest of my life if I want to. Spanning not just decades, but centuries, is the mark of true genius."

Further probing reveals that Beck has hobo credentials of his own.

"I haven't really ridden the rails, but I've ridden 'the dog'."

No, he's not admitting to bestiality.

"I had a summer once of sneaking onto Greyhound busses, which was pretty easy to do. It was the summer of '89, and they were having a strike at the time, so the guys who loaded the baggage were also doing the driving. It was fairly chaotic and the buses were all overcrowded so it wasn't hard. It's impossible to ride the rails now because it's all enclosed and you can't sneak on."

Another living legend that he's been getting palsy-walsy with recently is David Bowie.

"I haven't met him in person, but we talked on the phone once for about an hour, and it was probably the most inspired and engaging conversation I've ever had," he enthuses. "I've met some of these cats who've been doing it for ages and ages, and some of them are very bored. Some of them seem kind of tired. Some of them seem nice, but not really interested. Bowie, though, is completely on fire. I had more to talk to him about - y'know, random things from Koyoto to comic-book artists - than most people I meet of my own age.

"I actually did a remix of 'Seven' for him, which is very sparse and minimal. My music's got very dense and complicated in the past few years, so I thought, let's go in the opposite direction. I really must ring the record company up and see if he liked it."

More mouthwatering still is the cover of 'Diamond Dogs' that Beck is recording for the new Nicole Kidman and Ewan McGregor movie, Moulin Rouge. With Jay-Z and Aaliyah man Timbaland producing, it's likely to be in the same mutant R&B vein as his current album, Midnite Vultures.

"I've been listening to this music heavily over the last five years The more I listened to contemporary R&B stations and hip hop, the more I became interested in that kind of music. And I really wanted that to inform Midnite Vultures and consciously make it contemporary, but not in a trashy way. Take all the things that I like about contemporary R&B, but without all the gunk and slickness and tasteless elements of it."

Would he be referring to the middle-class American who last year took a pop at our own gangsta wannabe, Shane Lynch?

"I'm not even talking about Puff Daddy. I'm just talking about this whole modern era of R&B and hip hop - R.Kelly, Master P, Bone Thugs 'N' Harmony. So many bands that come and go, you never ever find out what their names are. But you hear the song over and over for six weeks, and then they're gone. I love the stuff that tries to sound slick, like a Kenny G record, but is just so undeniably ghetto. It's trying to sound all slick like Whitney Houston, but there's something awkward and haphazard and out of tune about it. Those are the tracks that I love. In 20 years or so, people will realise how amazing this music is."

Despite getting the thumbs up from such influential scenesters as Kool Keith and Snoop Dogg, Beck's audience remains predominantly white. It isn't something that he can do a whole lot about. Or if he can, he hasn't thought of it yet

"I don't think people in that world get where I'm coming from," he states. "I never pretended to be an MC. I always had my own style. I threw many of the hip hop rules out the window immediately. I didn't even try to be real. There's very stringent rules as to how hip hop's made. It's very protective, almost like the way the Germans make beer. You can't fuck with the formula at all."

They may be poles apart musically, but attitude-wise Beck and Moby are very much kindred spirits. Never happier than when they're fucking with people's preconceptions, their willingness to abandon a winning formula and head off in a new direction, makes them far more punk rock than your Green Days and Offsprings.

"With most top 40 music, you might as well be writing a jingle for soft drink," he growls. "The music sounds like those commercials, and the videos look like those commercials. It'd be nice if some of my fellow artists started taking more chances. The Moby thing's been said to me a few times recently, and yeah, we're both thorns in our record companies' sides (laughs)."

With Witnness one of the last major gigs he's doing in support of Midnite Vultures, Beck is currently deciding 'where to' next?

"I think the next album's gonna have a lot more rock," he confides. "I'm at a crossroads because I have lots of ideas, but you're only allowed to put out 10 or 12 songs every two or three years. I've lost count of how many songs I've written - it could be up in the thousands - but if you put out too much music it tries people's patience.

"I had an obsession with R&B, and I got it out of my system with Midnite Vultures. I know that record wasn't exactly what a lot of people wanted to hear, but I loved making it, and I have a whole other album's worth of material we recorded for it. I also have several tracks I've been working on with the Dust Brothers over the last two years, and we still have unreleased stuff from Odelay in the can. I want to do an album in Spanish, and I've wanted to go to Nashville and do a straight country record since I first picked up a guitar.

"I also have a record of solo acoustic finger-picking songs that I've been working on for 10 years. Then I have an obnoxious rock record I've recorded, and there's a record I want to make with Kool Keith that we've finished three tracks for. I'd also like to do a covers album."

Talking of which, how comes he's never made it on to a Black Sabbath tribute record ?

"The quick answer is that nobody's asked me. I'd love to dismantle 'Changes', though, and stick it back together with, I dunno, beats and a brass section. Or a banjo, maybe. I was supposed to do ones for Kraftwerk and Bruce Springsteen, but there are only so many hours in the day. It's the same with remixes. I did a Bjork song a couple of years ago, and Air's 'Sexy Boy', but nothing since, apart from Bowie."

We'll be back after this short commercial break

"I've got a B-sides album, Stray Blues, which came out during the summer in Japan. There are no plans at the moment to release it here, but you can order it direct from the www.beck.com website. I've talked to the guys in the office, and they've promised me that they won't steal your money."

Although he's had to cut back on the musical thievery - "the people you sample end up making more money than you do" - Beck's main source of inspiration is still his record collection.

"I would love to come out with something that doesn't sound like anything that ever happened before," he recently told Spin. "But to do that you need to surrender all earthly pleasures and weaknesses. How can you not be seduced by an AC/DC guitar riff? Or a fat beat from a Gap Band song? These are musical hamburgers. These are pleasures we cannot deny ourselves."

If those are musical hamburgers, what are the fillet mignons?

"Um, there are a lot of them. Sly & The Family Stone's Stand. Woody Guthrie's Dustbowl Ballads. Leonard Cohen's Songs From A Room. I go through a lot of music. I don't really have any favourites. I have songs I like, or part of a song I like from one album. It's rare that you find an album where every part is great. I listened to side two of Abbey Road recently, and I thought that was pretty amazing. I hadn't listened to it since I was a kid, and I never noticed how the songs go into each other continuously. I think that's really interesting."

Suddenly, Winona Ryder walks in, French kisses Beck for, oooh five minutes, and then proceeds to tell me how blissfully in love they are. Actually, I'm just making that up to cover for the fact that a nice, but very strict, P.R. person calls "time" on our interview before I've had a chance to ask him about his private life.

If you weren't at Fairyhouse to see his James Brown meets Aerosmith rock 'n' soul revue, well, I'm afraid you missed the gig of the millennium so far. Joined on stage by a motley assortment of rappers, scratchers and trombone players, the Y2K Beck bears no relation to the slacker Dylan-alike who first graced these shores in 1995. Now that Prince has descended into self-parody, he really is the King of Eclectics - a sexy divil who recognises that Marc Bolan, Robert Johnson, Marvin Gaye and W. Axl Rose are of equal import.

"I like chaos taking yourself and the audience into the unknown, so no one is quite sure of what's going on," he reflects. "I love the kind of abandon that you feel onstage when your own will has been removed and you are completely vulnerable and no longer in control. You may look vulnerable. You may even look idiotic, but there's something honest and revealing going on."

Beck's new single, 'Nicotine & Gravy', is out now on Geffen.