With many soul divas as famous for their hissy fits and colossal egos as their music, encountering two of them in the same country is rare enough, never mind in the same room. But one of Mary J Blige's first hits was a cover of Rufus and Chaka Khan's Sweet Thing, and she has clearly never forgotten the leg-up. Later, she refers to her heroine - who has overcome similar drug and relationship problems - as "my favourite person in the whole music industry", and repays the debt by offering Khan a platform to rescue a career that has gone as haywire as her hairdo. Sadly, while the big lungs remain, Khan is directionless, wailing her way through a covers-heavy set that only sparks into life with her own I'm Every Woman, which was a hit 25 years ago.
If Khan wants some tips on how to stay with the game, she should watch Blige. Blige enters to a montage of magazine covers that reveal more image changes than peak-era David Bowie, who has currently decided to settle on luxuriant blond locks. The Queen of Hip-hop Soul skips mercurially between genres, surrounded by dancers that recreate the authentic feel of a Broadway show.
After the entertainment comes the emotional knock out. Lyrics about domestic violence are vividly illustrated by dancer-actors - as the male yanks the female by the hair, you can feel the pain, which is presumably the point. Blige urges the children of the ghetto to "keep their heads high" and delivers the killer line: "I was a child of the ghetto too," referring, of course, to her own childhood. The struggle for survival, first, and then success erupts in a show-stopping version of No More Drama.
This is an extremely clever show that takes soul music to the theatre - even the man seeing to the mic stand dances while he twiddles.
The moral of this is that we only get one life, and the unfolding plot tells the story of how Mary hated herself at first but then learned to love herself, sentiments with which Manchester noisily concurs.
· At the NEC Arena, Birmingham, tonight. Box office: 0870 909 4133.
