Avril - and previously announced Katy Perry - will join "Idol" when it comes to Los Angeles this week for the final two days of auditions.
The "Sk8er Boi" singer will help judges Simon Cowell, Randy Jackson and Kara DioGuardi decide who is worthy enough to get a "Golden Ticket" to Hollywood.
The singers won't be the first to sit in at the judges' table since the news that Paula wouldn't return for Season 9.
As previously reported on AccessHollywood.com, Victoria Beckham served as a guest judge in Denver and Boston, Mary J. Blige shared her expertise in Atlanta, Joe Jonas and Neil Patrick Harris guest-judged in Dallas, Kristin Chenoweth joined the panel in Orlando and Shania Twain sat at the judges' table in Chicago.
Season 9 of "American Idol" returns to FOX in January 2010
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