What song did Avril Lavigne sing at the 2003 Brit Awards last night?

I guess the post title is pretty self-explanitory…

Anyway, I grew up in the 1970’s and am not knowledgable of current pop music. I was channel surfing last night and caught the end of Avril’s song and was impressed! For the life of me I can’t recall any lyrics from the song to Google though. I tried the Brit Awards site but there’s no mention of which song she sang.

Please help! Thanks!

MTV UK says her “memorable performance” was Sk8r Boi “backed by 20 drummers.”