L.A.'s Nokia Theatre was bursting with star power Sunday night.

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The 2011 American Music Awards included a number of powerhouse performances by Jennifer Lopez, Katy Perry, Nicki Minaj, Drake and more.

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Some of the most memorable moments of the evening were thanks to "Party Rock Anthem" singers LMFAO, who were joined onstage by Justin Bieber and a pants-less David Hasselhoff.