Lionel Richie, Carlos Santana, Cyndi Lauper, Queen Latifah, Black Eyed Peas and Keith Urban are among the artists scheduled to perform on Wednesday's finale before either Allen or Lambert is crowned the eight season champion.
Previous "Idol" winners David Cook and Carrie Underwood will also croon on the two-night finale. Underwood will perform on Tuesday's episode, which will feature Lambert, a 27-year-old theater actor from San Diego, and Allen, a 23-year-old college student from Conway, Ark., duking it out for a record contract and the title of "American Idol."