Flight of the Conchords, NIA, Birmingham<br/>Pavement, Brixton Academy, London

Jemaine Clement and Bret McKenzie's anti-folk television duo are superstars of comic pastiche, now the Conchords show they're also top flight on stage

In spite of two hit HBO series syndicated worldwide, millions of DVD and album sales, and now big enough to fill 12,000-seater hangars such as the NIA, Flight of the Conchords still don't look the part, with the indie/lo-fi sensibility of the show, the zen stoner feel and the in-jokey nature of its humour.

Flight of the Conchords – real version (or semi-real, but we'll come to that) – are the genius double act of Jemaine Clement and Bret McKenzie. Half-Maori Jemaine is the nerdy, bespectacled Jeff Goldblum lookalike in a plaid shirt whose speciality is putting on super-falsetto or basso profundo voices while playing an unconvincing Mr Loverman. Bret (or "Brit" in his Kiwi accent) is the bearded pretty boy in a washed-out Silver Lions 20/20 T-shirt who specialises in pulling the mock-soulful facial expressions of the pseudo-sincere rocker.

Flight of the Conchords – fictional version – are an anti-folk duo from New Zealand living illegally in New York trying to break America. It's the comedy of failure; it's a subtle satire of the immigrant experience, and it's also an elongated buddy movie in half-hour instalments. But the real hook – the reason why it's adored by so many – is the music.

The plot premise that the Conchords are desperate genre-hoppers allows them to tackle any musical style they choose. Their pastiches are never too on the nose, executed with the subtlety and wit of men who know music inside out. The joke's always ultimately on the Conchords themselves.

We get homages to Prince on "The Most Beautiful Girl in the Room" ("You could be a part-time model ... an air hostess in the Sixties ..."); Barry White on "Business Time" ("I take off my clothes, but I trip over my jeans, and I'm still wearing my shoes ... but it's OK, because I turn it all into a sexy dance"); Marvin Gaye on "Think About It" ("Why are we still paying so much for sneakers when you got them made by little kid slaves? What are your overheads?"); a 10cc/John Waite denial song in "I'm Not Crying" ("I'm cooking lasagna ... for one"); and the charity fundraiser "Epileptic Dogs" ("There's a golden retriever that's having a seizure ...").

Regardless of the humour, these are brilliant songs. The ultimate, also unplayed, is lighter-waving anthem "Pencils in the Wind", an extended stationery metaphor which is as silly as it is genuinely touching. I actually had it played at my wedding.

Tonight, using an assortment of miniature instruments and the New Zealand symphony orchestra (who is one cellist called Nigel), the Conchords perform highlights from their song-book, expanded to include verses unheard on TV, as well as a handful of brand new tunes, raising hopes that there may be a third series after all. "1353", a medieval folk ballad about "wooing a lady" and featuring duelling recorders, is crying out for a video.

A heckle of "Where's Murray?" (a reference to their hapless manager, played by Rhys Darby) is slapped down thus: "He's with all the other fictional characters of the world ..." There's an undeniable fiction/reality continuum with these guys. Bret and Jemaine are playing Bret and Jemaine, as proven by the knowingly tedious tour anecdotes about eating muffins in the hotel (not in the Aerosmith sense). How these perennial losers ended up playing the arena circuit is a hole in the plot that has yet to be explained, but everyone's laughing too hard to care.

When they aren't laughing, they're making ovine baas. Which eventually becomes too much for Jemaine, who's clearly encountered this one before. "You think you're so clever, but you probably don't know what you're saying in sheep language."

Speaking of pastiche acts .... When Mark E Smith first heard Pavement, he thought he was listening to one of his own live recordings from the mid-1980s. Smith's influence on Pavement's early material was blatant, most notably on the lopsided post-punk of "Conduit for Sale!", but there was also a melodic side to the preppy Californians, who were as much influenced by Jonathan Richman and the Modern Lovers as The Fall.

Pavement were always a difficult band to warm to. By accident or design, they epitomised the Slacker "movement" ("stasis" seems a more fitting noun), which was, in retrospect, a Clinton-era luxury. The Generation X-ers were afforded the freedom to sit around feeling misunderstood and letting their hair grow, but the time for slacking passed long ago.

Hearing their reunion gigs after a 10-year hiatus, then, one cannot escape a feeling of anachronism, and there's only so much Pavement you can listen to without wanting to scream at them to stand up straight, especially when the lead singer is 43.

Pavement's permanent listless vagueness was the sound of drumsticks gripped too loosely, guitars that hadn't been tuned for days, and a vocalist who sounded like Emo Phillips having a breakdown. A certain shambolicism is therefore part of the deal, but they're still woefully under-rehearsed. The once-gorgeous "In Her Mouth a Desert" falls to pieces midway through, and guitarist Spiral Stairs hits more bum notes than a proctologist's filing cabinet.

But when they're good, oh my they're good. "Zurich is Stained" and "Trigger Cut" are unbreakably beautiful, and when he directs his ire at other bands, Malkmus' lyrics are priceless. Take "Out on tour with the Smashing Pumpkins/Nature kids, they don't have no function/I don't understand what they mean and I could really give a fuck", or "What about the voice of Geddy Lee? How did it get so high? I wonder if he speaks like an ordinary guy ...".

Over their heads, a canopy of fairy lights hangs on sagging cables. They slouch, but they sparkle. Likewise Pavement themselves.

Next Week:

Simon Price sees Alicia Keys try to get thousands of Brummies to wail their love for New York