Actress Amanda Seyfried is apprehensive about playing porn legend Linda Lovelace in a new biopic, insisting it's "really hard and kind of terrifying" to tackle the tough role.

The Mamma Mia! star has replaced Kate Hudson as the adult actress-turned-anti-porn activist in the upcoming movie, opposite Peter Sarsgaard as Lovelace's husband Chuck Traynor.

Seyfried is "really excited" about the shoot, but admits she does have a few reservations.

She tells ABC News, "It's going to be really hard and kind of terrifying at the same time. I do have some liberties there but I am playing someone that existed in history and had quite an established reputation for something very extreme."

"She was such a different person than what we expect. It's a good story to tell, and I'm really, really excited about it."

Slideshow: 10 Sizzling Photos Of Amanda Seyfried