ZZ Top, Brixton Academy, London

By 1983, ZZ Top were already an ugly, less than youthful blues band. But few of their contemporaries, ugly or otherwise, played such a canny game with MTV. "Legs", "Sharp Dressed Man", "Gimme All Your Lovin'" - these were songs whose chart success was partly contingent on ace promo videos starring souped-up cars and leggy Texan gals. Meanwhile, the Top seemed content with clowning bit-parts involving furry guitars and what one suspected was a fair amount of perving behind biker shades. Am I implying that the music was secondary? Absolutely not. In bolting a synthesised backbeat on to the filthy chug of Billy Gibbons's guitar, ZZ Top revitalised Texan boogie.

That was 20 years ago, however, and the band are now in town to announce the arrival of Mescalero, due in September. The taut and infectious shuffle "Buck Nekkid" might be ZZ-by-numbers, but Mescalero also includes "Que Lastima", a banging techno-mariachi song sung entirely in Spanish. Together with the album's marimba-infused title track, it's further evidence that this "little ol' blues band" still likes to push the envelope.

When Gibbons and his bassist compadre Dusty Hill take the stage, the roar of approval is deafening. It's smiles all round, too, because the pair are wearing matching outfits of Stetsons, shades and ponchos that scream "Let us entertain you!" Deliciously, we acclimatise to all this as they stomp through "Gimme Me All Your Lovin'".

There is, of course, the matter of the beards. There's Frank Beard, ZZ Top's famously clean-shaven drummer. And then there are the beards sported by Gibbons and Hill: lengthy, two-pronged creatures so conspicuous and celebrated that they almost seem like extra band members. Hiding behind them, Gibbons and Hill can drop into choreographed moves without embarrassment, dancing through every hit from "Cheap Sunglasses" to "Legs".

All this showmanship is grounded in some fine close-harmony singing ("Pincushion", "Waitin' For The Bus") and some incredibly visceral music. Playing a guitar that was a gift from Bo Diddley, Gibbons unleashes scores of growling, low-register solos, the very best of which comes on "Rough Boy", where his use of false harmonics and controlled feedback seems magical.

Hirsute yet astute, ZZ Top are still consummate entertainers, then. They remind you how much fun the blues can be, yet never sound less than wholly authentic. As they encore with 1973's "La Grange", its riff long since stolen from John Lee Hooker, I'm wondering if Gibbons's and Hill's beards are insured. I'd have thought so, wouldn't you?