Sarah Paulson stunned The Goldfinch director John Crowley when she underwent an image overhaul to audition for the role of Xandra.

Speaking to reporters at the Toronto International Film Festival, Paulson revealed she had her heart set on the role from the moment she read Donna Tartt's bestselling novel, even though the role was far removed from her natural image.

"I had read it years ago when it first came out. And I just remember saying out loud, 'If they make a movie of this, I would love to play Xandra'," she told BBC News. "And I was not the choice of John Crowley at the beginning. I think he had a particular image in mind, which is the image you see in the movie, which is not how I usually present."

To transform into Xandra, the spray-tanned girlfriend of the book's protagonist Theo's dad, she took extreme measures, surprising Crowley and producers.

"I hired someone to put a wig on my head, I got a spray tan, I brought cigarettes into my audition, spent an hour in my car screaming to make my voice have a bit of a rasp, because that's how Donna Tartt describes Xandra's speaking voice," Paulson added. "I did all that and made the tape and I got a call saying, 'Uh-oh, you did very well'. And they weren't expecting that. Sometimes I think you have to change your physical appearance... I understand why it was hard for people to make the jump."

Confessing he was stunned by the audition, the director said: "When she was mentioned for Xandra I was like 'really?' She's great but I couldn't quite see that.

"But boy, is the last laugh on me. She went at it with a great character actor's eye for detail, a love for the book, and she just colonised that role in a way that was amazing."

The Goldfinch debuts in cinemas later this week.