Two-time Grammy Award winner Kelly Clarkson and punk-pop dynamo Avril Lavigne are set to perform on Teen Choice 2007 Sunday, Aug. 26 (8:00-10:00 PM ET live/PT tape-delayed) on FOX. Clarkson will perform the "Never Again" and Lavigne will sing her infectious hit "Girlfriend." As previously announced, Hilary Duff and Nick Cannon will co-host the ninth annual special, where the coolest stars will receive coveted Teen Choice Surfboard awards.

After the tremendous success of 2004's "Breakaway," which sold 6 million albums in the U.S. and 11 million worldwide on the strength of such No. 1 hits as "Since U Been Gone," the title track, "Behind These Hazel Eyes," "Because of You" and "Walk Away," Clarkson focused on making the kind of album she wanted to make for her third effort, "My December." This year, Clarkson could walk away with a Surfboard for her single "Never Again", which is nominated for Choice Music: Payback Track.

Lavigne's "The Best Damn Thing," which recently hit platinum status, is the follow-up to her album "Under My Skin." At Teen Choice 2007, Lavigne could get a Surfboard for Choice Music Single for "Girlfriend." She released her debut album, "Let Go," in 2002, when she was 17 years old. That album snagged eight Grammy nominations and four Juno Awards (including Album of the Year and New Artist of the Year), spawned the anthemic hit singles "Complicated," "Sk8ter Boy" and "I'm With You," and sold more than 16 million copies worldwide. Lavigne has recently branched out into acting, appearing in Fast Food Nation and lending her voice to the animated film Over the Hedge.

Celebrities scheduled to appear at Teen Choice 2007 include Jessica Alba (Fantastic Four), America Ferrera (Ugly Betty), Megan Fox (Transformers), Emmy Rossum (Andrew Lloyd Webber's The Phantom of the Opera), Lauren Conrad (The Hills), Miley Cyrus (Hannah Montana), Anna Paquin (X-Men), Eve (Barbershop), Dane Cook (Good Luck Chuck), Jared Padalecki (Supernatural), Taylor Kitsch (Friday Night Lights), Ryan Reynolds (Just Friends), Zac Efron (High School Musical), Dwayne The Rock Johnson (The Game Plan), Rob & Big (Rob & Big), and musicians Bow Wow, Ashlee Simpson, The Jonas Brothers, Omarion and Sum 41. Other performers and presenters will be announced soon.

This year the coolest stars will receive coveted Surfboard awards in categories such as Choice Breakout TV Show, Choice Sidekick, Choice Rumble, Choice Rock Track, Choice Athlete and Choice Chemistry. From now until Sunday, Aug. 19, teens can vote on the nominees in all categories on fox.com/teenchoice and Verizon Wireless customers can text* the word VOTE to 8905 to cast their vote for Choice V CAST Video Series or Show on Mobile, Choice Summer Movie, Choice Summer TV Show, Choice Summer Song and Choice Summer Artist.