By Kate Nettleton, campaignlive.co.uk, Wednesday, 18 February 2009 04:45PM
The 60-second ad, which will also run across Europe, was created by Mother and features the Welsh singer taking a "Diet Coke break" before performing a gig.
During her break, the singer takes a sip of the drink before riding around on a bike and singing a cover of the Sammy Davis Jnr song I Gotta Be Me.
The ad, which marks a departure from Diet Coke's series of "hunk" ads, aims to show an image of women as strong, confident and in control.
This article was first published on campaignlive.co.uk