Franz Ferdinand, Thekla, Bristol

It isn't out for another six months but I predict Franz Ferdinand's third album will be an unbridled, feral monster of a groove. Well, that's how it sounded in the crammed cargo hold of the Thekla, a converted coal barge. A far cry from the sold-out Alexandra Palace run of four gigs in 2005, the Glasgow quartet decided to give their fans an intimate taster of their new material this time: Franz in the raw, crowded on to a tiny stage, reconnecting with their roots – the days before their elaborate choreographed and propped arena shows.

It's been nigh on five years since Franz sparked an angular post-punk revival, saving British music from sinking into the junky morass à la Libertines or the creative dead-end of garage-rock. But there's been such a flow of younger pretenders rising up, the original trailblazers were in danger of being sidelined. You Could Have It So Much Better was a rather apt title for their second album, rushed, over-produced and creatively threadbare.

Tonight Franz almost ignored it, focusing instead on new tracks and their first body of work. "Dark of the Matinée", "Take Me Out" and a frantic version of "Michael" gets everyone jumping. Even on first hearing, the new songs are also granted a massive seal of approval. The super-sharp guitar stabs that made Franz's name are still there but Nick McCarthy has a lot more to do on the keyboards and Paul Thomson's driving beats have reached out to far more expansive and funky domains.

One song has a similar delectable and squelchy electronic sound to that which underpins Stevie Wonder's "Superstition"; another has the most banging glam stomp you can imagine. For the finale, two extra drummers are required for a bombastic extended multi-percussive break. Welded on to a disco-punk simile of Giorgio Moroder's "I Feel Love", it is intoxicating.

The new and the familiar coagulate in a fiery fury, as lead singer and guitarist Alex Kapranos unleashes an increasingly squally guitar sound, edging close to an acid-fried rock freak-out. Forget the stadium shows, at these sweaty little gigs Franz have rediscovered intensity, passion and most importantly, have built on a foundation of gritty, fierce and exhilarating funk.

"Burn this city," they chant for the encore, "This Fire". It's such a scorcher it's a wonder Bristol wasn't reduced to ashes.