'I'm Going Down' singer Blige and last season's American Idol runner-up Alaina will take to the stage on Thursday, March 8, it has been announced.
Fox has yet to reveal what song Blige will be performing. Alaina will sing her track 'Georgia Peaches', taken from her debut album Wildflower.
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Blige will also serve as a mentor for the Top 13, helping them with their performances. The female finalists will be tackling tracks by Whitney Houston, while the male finalists will be singing songs by Stevie Wonder.
The Top 13 were named this week following two nights of semi-final live performances.
Hollie Cavanagh, Colton Dixon, Heejun Han, Jermaine Jones, Skylar Laine, Joshua Ledet, Shannon Magraine, Phillip Phillips, Jessica Sanchez and Elise Testone were voted through to the next round by the public.
Judges Jennifer Lopez, Steven Tyler and Randy Jackson then advanced Erika Van Pelt, Jeremy Rosado and DeAndre Brackensick as their wildcard picks for the season.
American Idol airs Wednesdays and Thursdays on Fox.