MTV: CHRISTINA STRUTS THROUGH EXPRESS

Before she even took the stage at the American Music Awards on Sunday night (November 21), Christina Aguilera had already watched a series of over-the-top performances from show-opener Rihanna, an uncharacteristically sedate Miley Cyrus, the always outrageous Katy Perry and a piano-tinkling, snow-shower summoning Taylor Swift.

In other words, she saw the future, and it was a cornucopia of female stars who have taken cues from her career -- and she made sure to show them that she's still got a few tricks up her sleeve.

Preparing to make her big-screen debut alongside Cher in the upcoming "Burlesque," as promised, Aguilera gave a sneak peek at what we can expect in theaters. "It's going to be fantastic," she told MTV News. "And it will give you a fitting little look inside the movie."

Seated in a chair with her back to the audience and wearing a black spangly bodysuit, knee-high boots and a bowler, Aguilera snapped her fingers and leaned into the jazzy, skittery rhythms of the new tune "Express (Burlesque)." As the camera pulled out, it revealed a set made up to mimic the backstage at a burlesque club, with Aguilera surrounded by a squadron of equally scantily clad dancers.

She flashed back to the "Dirrty"-era Xtina, straddling and shimmying on the chair, then busting into the song's uptempo chorus and showing off the throaty pipes that made her a star. Shaking her hair along with her lingerie-clad dancers, the singer was clearly back in her element, mixing club beats with a throwback, "Free Your Mind"-style R&B vibe and strutting across the stage confidently with her patented growly sass intact.

Even after a career spent in the spotlight as a child star on the "Mickey Mouse Club" and a pop icon since her late teens, Aguilera said the difficulty of trying to reproduce the dancing in the film for the AMAs took a toll on her. "It will be another very new challenge for me," Aguilera admitted beforehand. "My legs have been incredibly sore as I stepped into the role of Ali for this." In the film, Aguilera plays a small-town girl with big dreams who stumbles on a burlesque club owned by the feisty Tess (Cher).

Aguilera added that, while relearning the dance routines was grueling, the choreography is amazing. "You're going to get quite the show," she promised. "Quite the spectacle."

While Aguilera is new to the world of acting, Cher told MTV News that the pop star can dish it out with the best of them. "The scenes that she and I had together, I really enjoyed, and I really believe that she's got definite chops," she said. "We worked well together. I enjoyed all of it, and she was toe-to-toe with me the whole time."

What did you think of Christina's performance at the AMAs? Share your reviews in the comments!