Al Green is the last of the American southern soul giants of the 1960s and 70s, a survivor where Otis Redding, Wilson Pickett and Sam Cooke have fallen. Yet tonight's rare show by one of music's living legends is a bizarre mix of the profound and the perfunctory, an exercise in genius carefully rationed.

His current repertoire is a gospel/R&B revue: Green famously devoted himself to gospel music in 1974 after being attacked by a former girlfriend who then killed herself, and he only returned to secular music five years ago. Here, he is part evangelical preacher, part stand-up comedian. His sermonising is clearly heartfelt, yet is punctuated with Richard Pryor-style gurning.

Thankfully, his magnificent voice remains intact. Green is a fantastically sensual singer with few equals: his pitch and tone are perfect on his signature tune Let's Stay Together, while on Tired of Being Alone, he casually unleashes a dazzling falsetto, genuflects and grins like the happiest man alive. The gospel section could be a dull interlude, were it not for the fact that Green makes even pious celebrations of the divine sound carnal. For Everything's Gonna Be Alright he performs a peculiar rabbit hop across the stage, then body-pops like a man 20 years his junior.

Nevertheless, this slick - and short - show is decidedly cursory in parts. Green spends half the night handing out red roses to devotees with a fixed Vegas smile, while his effortless charisma only just redeems a truly excruciating medley of his own hits and a miscellany of Motown classics. The irony is that an unnamed, delicate ballad from his imminent album is far superior, Green interrupting its luscious progress with spontaneous howls at the sheer, untrammelled joy of singing.

This legendary alchemist may have earned the right to coast, but if he puts his mind to it, he has more to offer yet.

· At NIA Academy, Birmingham (0121-357 0000), on Wednesday. Then touring