PJ Harvey stalks on stage, alone, guitar already slung over her shoulder, red sparkly dress glittering underneath. She plays the first severe chords of Rid of Me, smiling demurely from under her harsh black fringe at the packed Shepherds Bush Empire, then moves to the microphone and sings the first line: "Tie yourself to me..."
It's a song of degradation, of refusing to be dumped, and yet singing it, Harvey radiates only power. We could be on a rollercoaster, such is the adrenaline rush her performance induces. She ends the song yelling the chilling demand, "Lick my legs, I'm on fire" over the audience's cheers. It's one of those life-affirming moments to remind you why live music is unbeatably thrilling.
If the rest of the show doesn't quite live up to its incredible beginning, it's down to one thing only: Polly keeps putting down her guitar. It's not that her other two guitarists are inadequate - their sound is fearsome, cavernous, graceful - or that her jittery dancing isn't enjoyable to watch. It's just that she looks so sexy with a guitar, projects such confidence. When she stamps a twinkling foot in strappy four-inch heels on her effects pedal, it's unspeakably provocative. When she stands centre stage in the classic rock pose, shoulders back, pelvis thrust forward, lovingly wrenching those six strings, she challenges you to count her the equal of all those male axe heroes.
Of course, Harvey is playing up to stereotypes even as she demolishes them. She knows, for instance, that the men in the audience aren't quite as riveted by the pink cowboy hat, leopard-print platform shoes and furious playing of her band's second guitarist, Laika's Margaret Fiedler. But at least when Harvey plays, she becomes singularly inspiring. When she dances, she is more ordinary, more like other female singers, looking good for the boys.
These are thoughts to fill you with guilt, because Harvey looks so content, happy not to be shackled by her guitar, to be able to do little cha-cha-cha moves with her feet and twirl her arms. Particularly on the more visceral tracks from last year's album Songs from the City, Songs from the Sea, she prefers to be the calm centre of her music's maelstrom, nonchalant with a pair of maracas.
Big Exit and Kamikaze, enormous on record, here grow bigger still, detonating rhythms, churning out energy. When Fiedler's effects pedals momentarily stop working you realise how pristine the sound is. For these songs Harvey makes her voice sound metallic, rusty and scratchy; elsewhere, what you appreciate is the clarity of her voice, its beauty. She sings This Mess We're In and it's earthy, seductive, quite unlike Thom Yorke's eerie wails on record. There are hints of Patti Smith, but they don't detract from Harvey's own strength.
Despite the misgivings, it's a superb show, one to make you leave the venue feeling inches taller. Harvey is one of the most compelling songwriters around, and her set, spanning her career from 1992's Sheela-na-gig to the present, shows she's only getting better.
At the Shepherds Bush Empire, London W12 (020-7771 2000), tonight.