Amy Winehouse, Jazz Café, London

In the wake of Norah Jones, the record-buying public has been swamped by a wave of female singer-songwriters with heartfelt sentiments and rootsy tastes, Katie Melua and Joss Stone among them.

With her exotic looks and love of Sinatra betrayed on her debut album, Frank, Amy Winehouse has been posted in the same pigeonhole. This despite a batch of candid, gritty songs that sets her apart from the soft-focus slush of Jones and co. Most memorable is "Fuck Me Pumps", for its bitchiness, while the stark honesty in her somewhat confrontational confessional "I Heard Love Is Blind" and the pleading for masculinity in "Stronger Than Me" single-handedly threatened to reignite the gender war.

This month, Winehouse embarked on a handful of low-key dates to show that she was more jobbing musician than upcoming starlet. Low-key, that is, until she received two Brits nominations, which have put her into competition against Dido and Sophie Ellis-Bextor.

No surprise, then, that on Tuesday evening the venue was packed and the crowd expectant, especially as this Camden leg was home turf for the north-Londoner. The 20-year-old spent the time between songs pointing out her mates in the audience.

Winehouse revealed herself to be as forthright as her songs, in pointed heels and a plain black dress with straps that insisted on slipping off her shoulders throughout her set. She struggled to keep them in check as she wielded a guitar in a tentative manner that belied her PJ Harvey look.

Winehouse stood out from her unobtrusive backing-band, recently doubled in size to six members by the introduction of a smooth brass section. Her album takes in swing, hip hop, soul and jazz, but the musicians here provided a more perfunctory backing. And quite rightly, for the star of the show was Winehouse's extraordinary voice. Despite her age, she sang in a deep, smoky manner that brought to mind veterans of dingy clubs, most notably Cleo Laine, on the sultry "Round Midnight" and "In My Bed". With the funky "Mr Magic", Winehouse hinted at the sass of Lauryn Hill.

It was, though, a surprisingly demure performance. On record, Winehouse is often jaw-droppingly direct, a motormouth who speaks before she thinks. She could have let the songs do the talking, though her most incisive lines were lost in a scat singing-style of running words together in one sweet flow. Only at the end did Winehouse make clear that she was unhappy providing background music for polite dinner parties, when the brass section departed for a stark, stripped-down "Pumps".

As is now common, Winehouse has come a long way very quickly, with surprisingly unpushy backing from the Pop Idol impresario Simon Fuller, so it is bound to be a while before she gains the confidence to match her studio abilities in live performance. In fact, she always said her original ambition was to be a lounge singer, and that could turn out to be a disappointingly accurate prophecy.