(Cover) - EN Showbiz - Chers voice is so powerful it blew away the director of her new movie Burlesque.

Steve Antin helms the movie, which also stars Christina Aguilera. Christina plays Ali, a small-town girl who moves to Los Angeles and finds herself catapulted into the spotlight by a bar owner called Tess, portrayed by Cher.

The movie includes a lot of singing and dancing, and Steve admits being shocked when he heard 64-year-old Chers voice for the first time.

"What was extraordinary about this was Cher was doing her solo, You Haven't Seen the Last of Me, he told MTV News. "I could hear her over the playback, perfect pitch. She still has that powerful of a voice and I was just blown away because the playback is so loud. Same with Christina, I could hear her singing over the playback and I was just completely moved and everybody was blown away by it."

Steve refused to let people lip-synch while shooting their scenes. He wanted the movie to look as natural as possible, and feared it would be obvious if the stars werent really singing.

He admits it made things hard, especially combined with the difficult staging, lighting and smoke machines, but hes adamant it was the right choice.

I always ask singers to sing every take; you have to," he said. "For me, I have to because you create a completely different image when you're lip-synching. Your whole entire body moves differently, so I would always ask the singers to sing during their takes. (C) Cover Media