Arcade Fire, Hackney Empire, London<br/>Dr John, Shepherds Bush Empire, London

To affectionate boos, Win Butler smirks, "I think England have got a real good shot in the World Cup. Hey, I'm just practising my banter for Reading and Leeds ..."

A joke? From Arcade Fire? What is the world coming to? It isn't the only thing that's changed about the Canadians lately. Take "Month of May", one of the leaked tracks from forthcoming third album The Suburbs. A piece of tunnel-vision amphetamine boogie in a Stooges/ Velvets/Suicide/Femmes style, it rattles and screeches along like a runaway train, while Butler spews sharply self-aware words about the pains of pouring your heart out on record for an uninterested audience: "Some things are pure and some things are right/But the kids are still standing with their arms folded tight ..."

Arcade Fire are the last band in the world you'd expect to release something that rocks that hard while poking fun at themselves. Then again, Win Butler – a man who always looks like he's been rained on, even in high summer – is also, surely, the least likely frontman to "do a Bono" and go on a meet-and-greet walkabout. But during new single "We Used to Wait" he does just that. By the end of the song he's got a taste for it and goes crowd-crawling. If he tries that in a field in August, hand him back carefully: he might snap.

The single contains the regretful line "we used to write letters", and much of the new material seems concerned with mourning lost youth and the estrangement of friends and lovers.

Of the familiar, festival-friendly songs, a xylophone-tinkling "Intervention" pleases the crowd, but it's an astonishing "Neighbourhood #3 (The Power Out)" which really hits the spot. I can't imagine how it must feel to be in a band, play a song that crackles with this kind of magic, and to get this kind of reaction. If I had any hairs on my neck, they'd be bristling.

Arcade Fire have rediscovered their sense of fun, although from Régine Chassagne's lemon rag-doll dress, Tim Kingsbury's blood-stained shirt and the singer's brother William's penchant for barrelling into everyone, yodelling into a megaphone and banging a drum, maybe it never left them. There's no doubt that Win Butler's inner rock-

poet-messiah is itching to get out, and one day he will release a solo album and it will stink to high heaven. It takes the strength of the other seven members to keep him in check.

When does the inauthentic become the authentic? About 40 years seems to do the trick. In 1968 Mac Rebennack, a jobbing session musician and sometime A&R man from New Orleans, created the character of Dr John Creaux, "The Night Tripper", a high priest-like band leader who made a heady gumbo of cajun, zydeco and voodoo blues, sung in a pidgin hybrid of English and Creole, as well as peculiar flashes of Noo Yoik. Four decades on, the faker is realer than real; the character inhabits Rebennack as much as vice versa, and Dr John is now, along with Allen Toussaint, one of the twin patron saints of New Orleans music.

If this review is crammed with strategically placed N'Awlins imagery – clichés, even – then I'm only learning from the great man. If there's one thing Dr John knows about, it's the power of imagery. This is a man who used to appear onstage in a puff of smoke, brandishing a boa constrictor and sprinkling glitter, while a practitioner of gris-gris magic would bite the head off a chicken and drink its blood. He may have mellowed slightly, but his grand piano is still draped in a black velvet spell mat covered in assorted bric-a-brac including a plaster skull – at least, I trust it's made of plaster.

The greybeard is 70 this year, and his band can't be far off it either, a veritable Bon Temps Rouler Social Club. But seniority doesn't stop Rebennack from getting up and dancing, and touching the floor with the palm of his hand without bending at the knee, just to prove he can.

Strangely, his most famous song is omitted tonight: "Walk on Gilded Splinters", a seven-minute badass incantation in which he visualises his "enemy at the end of a rope", whose definitive cover by Marsha Hunt is a thing of mad magnificence. Instead, from the same album (1968's classic Gris-Gris) we get "Mama Roux", which proves that Cuban rhythms have always reached Louisiana across the Gulf of Mexico.

In a set which kicks off with the gloriously titled "I'll Be Glad When You're Dead, You Rascal You", we also hear immortal cuts such as 1969's "Black Widow Spider" and 1973's "Right Place Wrong Time" which shows that, apart from anything else, Rebennack has a great funk voice.

What began as pastiche is now palpably the real deal, and even if it's all role play, Rebennack's charisma is delicious. This man will turn any venue into a French Quarter dive bar. Long may he get away with it.

Next Week:

Simon Price watches Pet Shop Boys illuminate the Blackpool strip and Klaxons dust off the rave alarm