The entertainers popped by the Nokia Theatre Friday to practice the performances they've planned for Sunday's show.
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Ke$ha was surrounded by male dancers as she bounced around the stage in sneakers, striped leggings and a torn black T-shirt. She played a giant golden drum, was carried aloft by her dancers and closed the rendition of her new hit "Die Young" by writhing on stage as fireworks rained down overhead.
Pitbull, fresh off his performance at Thursday's Latin Grammy Awards, arrived wearing crisp white pants, a red polo shirt and a tan blazer. After joking with his band in Spanish, he ditched the blazer and added shades to rehearse "Don't Stop the Party," for which he shares the stage with two drummers, two keyboardists, two ballerinas and a DJ.
Justin Bieber, Kelly Clarkson, Usher, Carrie Underwood, Taylor Swift, No Doubt, Christina Aguilera and Nicki Minaj are also set to perform during the three-hour ceremony, which will be broadcast live Sunday on ABC.
Stevie Wonder and Ryan Seacrest will also honor the late Dick Clark, who created the American Music Awards, at the 40th anniversary show.
Watch some of the best AMA moments from the past below: