Singer Avril Lavigne, shown this May in Los Angeles, will be a guest judge on American Idol.

Canadian pop singer Avril Lavigne has signed on to be a guest judge on the reality television talent show  American Idol.

Lavigne, whose hits include Complicated, will be on hand as Idol wannabes have their auditions this weekend in Los Angeles.

She'll share duties with I Kissed a Girl singer Katy Perry to fill the fourth judge's chair.

Timmins, Ont.-born Shania Twain has already filmed a segment for American Idol, overseeing auditions in Chicago.

She got on surprisingly well with the acerbic Simon Cowell, according to a report in People magazine.

Since Idol judge Paula Abdul announced she would step down last month, the producers have hired a series of celebrity judges to replace her.

Among them are Victoria Beckham, Mary J. Blige, Joe Jonas, Neil Patrick Harris and Kristin Chenoweth.

Season nine of the reality TV show is set to begin airing in January.

With files from The Associated Press