He's been Oscar-nominated for his portrayals of two US presidents - Richard Nixon in Oliver Stone's Nixon and John Quincy Adams in Steven Spielberg's Amistad - yet veteran actor Sir Anthony Hopkins was riddled with insecurity at the prospect of playing film director Alfred Hitchcock.
Crowning a half-century career during which he's variously played a vampire hunter, royal prince, Norse god and a priest, Hopkins still had major doubts about portraying the legendary British director.
"My insecurities started after the film - I caught a sight of myself on the video playbacks and took one look at it and didn't want to see any more because I wasn't sure that I'd got it right," confesses the 75-year-old actor about his starring role in Sacha Gervasi's biopic Hitchcock, which focuses on the director's battle to bring horror flick Psycho to the big screen.
"My insecurity was so deep - I just wanted to run away to Tierra del Fuego or somewhere like that," says Hopkins, whose Hitchcock commands the film alongside Helen Mirren's Mrs Hitchcock, Scarlett Johansson's Janet Leigh and Toni Collette's Peggy Robertson, the director's loyal assistant.
"But when I finally saw the film, I thought Sacha had done a remarkable piece of work and I was very pleased with what I saw," he says.
And while Hitchcock was notoriously overweight, Hopkins refused to pile on the extra kilos for the role, actually losing weight during his preparation: "I lost a lot of weight to get into shape for the part because I didn't want to put on weight," he says.
"The incredible work that Howard Berger did in creating the face of Hitchcock - we had to be very careful about me not being covered in make-up; not vanishing behind it.
"We did maybe eight tests and Julie Weiss, the wonderful costume designer, did the body. Once it was all put together, I felt like Hitchcock.
"The thing is to not do an impersonation because I think if it becomes pure mimicry, then something is lost and it becomes inauthentic. My task was to present a representation of what Hitchcock was like and hopefully reproduce his inner psyche as well."
Hopkins actually adopted the opposite approach for his portrayal of Pablo Picasso in James Ivory's Surviving Picasso 17 years earlier.
Discussing his process in Hitchcock, he says: "The script gave me a lot of the information I needed, and then I watched several documentaries and films on Hitchcock and began putting together all the pieces. But I wouldn't say I became Hitchcock. I don't do that, because I'd go mad. You can't just become anyone, but you just try to find a way to balance it so as to not make a caricature.
"I felt Sacha had unlocked the story that no one else had previously done."
While Hitchcock wrestled with alcoholism and depression during his later years, likewise Hopkins struggled with his own demons during his early career, abruptly quitting booze in 1975, claiming his recovery was because of his belief in God.
Having become a naturalised US citizen in 2000, the Welsh-born actor lives in Los Angeles with his third wife, Colombian producer Stella Arroyave, whom he wed in Malibu 10 years ago.
"I lead a simple life," he says. "No alcohol, no meat, no sugar, no dairy. I have no vices except the occasional cigar. My hair's falling out and I'm getting a little slower. But there's a little more cash in the bank, so I don't have a struggle. I can have a laugh now.
"Nor am I going to be modest anymore. I'm a movie star and it's lovely. It's uncanny, I'm exactly where I want to be in life. This life is precisely what I visualised for myself as a boy. It may sound arrogant, but this is what I dreamed of back in Wales.
"I have been given exactly what I wanted, and it's wonderful. The media always want to make out that I'm some problematic guy. Not true. No. I'm actually a lot of fun. I'm very easygoing. I'm always joking; always laughing."
Hopkins says he has also long been fascinated by Hitchcock.
"My first professional job was in the theatre in 1960 in Manchester and I remember Psycho was playing in Manchester, and I went and saw it one Sunday night in October 1960 and I don't think I've ever been so scared in my life," says the actor, who became a lifelong fan after that formative experience.
Of course Hopkins is no stranger to scaring audiences, perhaps best known for his menacing performance as charming serial killer Hannibal Lecter in The Silence of the Lambs, for which he won Oscar gold 22 years ago.
Known for his keen research, he describes Hitchcock as an utter paradox.
"He can be dark, troubled, cold, ruthless and obsessive and also big-hearted, warm and ingenuous," he says. "That was all part of his nature."