When American Idol winner Kelly Clarkson recently picked up two Grammys, she failed to acknowledge the show that launched her to stardom. Lately, she has also split with manager Simon "Spice Girls" Fuller and shifted from production-line pop into what she calls "soulful rock". Introducing a cover of Annie Lennox's Why, she says: "I want that kind of creativity, credibility and longevity."

Pop history is littered with teen market pop stars who have attempted to become "serious artistes", and if Clarkson is to fare better than them she might have to come up with something more exciting than so-so Avril Lavigne rock. In combat trousers, straightened hair and eyeliner, the Texan former club singer could be any Identikit pop robot. However, as cracks appear and she becomes more giddy and expressive, she reveals a more interesting side.

The 23-year-old southern belle has already battled an eating disorder (supposedly triggered by skeletal pop stereotyping) and is refreshingly at ease with displays of emotion. Her favourite words are "cool" and "awesome", but she displays endearing vulnerability. She sings Because of You seemingly on the verge of tears and the lyrics explain why: as a child she was not allowed to cry because it showed "weakness". As people sing the words back, there's a heart-stopping moment when she turns to her band in delight, but her musicians are looking away.

If Clarkson can get this vulnerability on record, she could yet emerge as some sort of reality TV generation Janis Joplin. A surprisingly impassioned cover of Tommy James and the Shondells' Crimson and Clover suggests an untapped vocal range. It won't be easy, but there's at least a chance that she might avoid the scripted fate of becoming a celebrity victim, pouring out woes of the pop world on daytime TV.

· At Hammersmith Apollo, London W6, tomorrow. Then touring.
· Box office: 0870 606 3400