At 63 years old, Cher admits it's not always pretty filming Burlesque with the much younger Christina Aguilera and Kristen Bell.

"It's a hard job. You get up at 5 a.m. and you try to look good," she tells Entertainment Tonight. "All these girls are, like, a third my age. That is rough."

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Cher is impressed with her less experienced co-stars though.

Of Aguilera, 30, she says, "I'm shocked, but she's really good. The other day, we were hamming it up so badly, so old, like vaudevillian. She was keeping up! She was hot. Her game is good!"

Says Aguilera, who makes her film debut in the flick (out this November), "It's really fun tapping into this whole new experience."

The singer plays Ali, an aspiring actress and dancer who moves to Los Angeles to make it big. Former Dancing With the Stars pro Julianne Hough also plays her biggest role to date.

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Of the skimpy costumes, Hough, 21, jokes, "My dad might have a hard time watching.  I like it. Obviously, I've worn next to nothing on the show [Dancing]. It's kind of second nature!"