Keira Knightley: Spanking? Only after vodka We were both very nervous about those scenes because they're not nice, and when we shot them I said to Michael, 'If you touch me I'm going to kill you. He said, 'Keira, you're tied to the bed at the moment. I don't think you're in any position to say that."" She laughs at the recollection. I said, 'Yeah, you're right. He's absolutely wonderful and we had a couple of shots of vodka before doing the scene and a couple of glasses of champagne afterwards. Knightley's portrayal of the Russian mental patient Sabina Spielrein, who recovered from her illness to become a leading therapist and intellectual colleague of Jung and Sigmund Freud (played by Viggo Mortensen), has won critical praise . I had no frame of reference for any of the things that she was going through so it was really sort of starting from scratch. I'd obviously heard of Freud and Jung, but I knew nothing about psychoanalysis. I knew vaguely that it was meant to be rooted in sexuality and that it had something to do with your parents, but, apart from that, I really didn't know anything else, so it was fascinating looking into it. She pauses and adds thoughtfully: "And very challenging. A lot of people say that acting is like therapy, but I don't go for that. It's not my cup of tea; it is for some people, but not me. I do, however, find it incredibly cathartic, and when you're playing something so dark you want to have a really nice time afterwards, otherwise it's far too depressing. The actual filming work was very focused and very creative, but at the end of the day we watched football - the World Cup was on - and drank beer, which was lovely. Since grabbing attention as the lively and lovely Jules in Bend It Like Beckham, Keira Knightley has proved to be a shrewd manager of her career, establishing herself as a Hollywood A-lister with the Pirates of the Caribbean movies and King Arthur and then eschewing big-budget blockbusters for smaller, more intimate fare. Pride and Prejudice earned her an Oscar nomination, and Atonement brought a Golden Globe nomination. She has also appeared in The Duchess, as the Duchess of Cavendish, The Edge of Love, playing Dylan Thomas's childhood sweetheart, and, last year, the drama Never Let Me Go, based on the novel by Kazuo Ishiguro. She has been dating musician James Righton, the keyboard player with the rock band Klaxons, since last February. She broke up with her previous boyfriend of five years, actor Rupert Friend, in 2010, and prior to that dated Irish model Jamie Dornan for two years, although romance is something she refuses to discuss. "It's far too personal," she says, deflecting an inquiry with a smile. The bubbly, outgoing teenager who was an ardent West Ham supporter and who talked freely and openly about her life is now a leading movie star, and, although she is still a cheerful Londoner with a keen sense of humour who enjoys a joke and a good laugh, stardom has instilled in her a certain wariness and an aversion to fame that wasn't there before. She is the first to admit she has changed. Yes, I was different then to the way I am now because you change with your experiences. It would be sad if you didn't, but my level of fame is not as big as Brad Pitt's, thankfully. At the time of the Pirates movies, I had a crazy time when very simple things were very difficult. I had about 20 guys standing on my doorstep, so going to the grocery store became incredibly difficult. I just didn't go out. When it gets to that point, it's not safe to go out and it just becomes impossible. Since then I've been doing different films and life in general has become much easier, so I can walk through the lobby of a hotel now. Knightley is again playing a Russian in her latest project, Anna Karenina, the film that has reunited her with director Joe Wright, who previously guided her in Pride and Prejudice and Atonement. Tom Stoppard wrote the screenplay, and the cast includes Jude Law, Aaron Johnson, Andrea Riseborough and Olivia Williams. Anna is a role that once again takes Keira into the realm of psychoanalysis, and she has been doing her homework by talking to an analyst and reading and rereading Tolstoy's novel. "We're all very aware that it's an incredibly difficult part and an incredibly difficult piece, and very often it hasn't worked," she says. But we have a brilliant team and a great group of actors, and we're going to do our best. Hopefully, Anna will come clear to me and hopefully it will work. A Dangerous Method" is out February 10.