Actress Hayden Panettiere guest-starred on the show and performed the 2001 hit "Lady Marmalade." Panettiere mimicked Aguilera's throwback look from the music video, complete with a huge blonde wig and a corset and gloves.
But the real surprise came when Aguilera joined Panettiere on stage to perform a few lines from the song. Unlike Panettiere, though, Aguilera is not lip syncing -- and the diva definitely still has her pipes.
Watch the teaser below.