It seems fitting that Erykah Badu and OutKast's Andre 3000 were once a couple (their break-up inspired OutKast's Miss Jackson). They represent the two most outré flowerings of notionally mainstream black music. Badu's latest album, her third, isn't actually an album at all, if her label is to be believed. Presumably shy of giving such a subtle, wilful record a full commercial release, they are calling it an EP, which seems somewhat disingenuous since the UK version has 12 tracks. There is, as Badu points out tonight, "no radio, no video", simply word of mouth.

Unfortunately the delicate experimentalism of Worldwide Underground is largely lost live. As with live hip-hop, the subtlety and shading are sacrificed in the interests of generating a groove. Snippets survive - particularly the stuttering pulse that leads gradually into I Want You, which posits the possibility of a black Laurie Anderson.

Badu looks fabulous - her extravagant afro resplendent, she looks the spit of Roberta Flack on the cover of the classic Quiet Fire album. She can also hit the notes, as a spellbinding, impossibly high peal worthy of Minnie Riperton in Otherside of the Game proves. For this audience, it seems, looking fabulous and hitting the notes is more than enough.

Worldwide Underground is not an esoteric record, but it does flicker with intriguing, unexpected nuances, and it would be wonderful if Badu were brave enough to try to translate them to the live arena. Her earlier songs still sound marvellous, though - a kittenish Appletree initially sung a cappella over an unusually well-timed slow clap from the crowd and the sinuous articulation of a groove that is On and On.

Actually, the bravest moment of the night isn't a musical one. In darkness, in between songs, Badu calls out: "Please leave Michael Jackson alone!" That really is something you're unlikely to hear anywhere else.