Keira Knightley downed shots and warned co-star security would ‘break his legs’ when filming risqué scene

She might have been on film sets since she was just 12-years-old, but even Keira Knightley needed a bit of liquid courage to psych herself up to shoot some of the scenes in A Dangerous Method.

The actress' teenage years were chock-a-block with huge roles in Hollywood blockbusters, such as Pirates of the Caribbean, but it seems her prior experience didn't help much when it came to preparing for the 2011 historical drama.

She played psychoanalysis pioneer Sabina Spielrein in the flick - which is set from 1902 to the beginning of World War I - who starts of as a patient of Swiss psychiatrist Carl Jung (Michael Fassbender).

Keira Knightley revealed she nearly turned down her role in A Dangerous Method because of some risqué scenes (Universal Pictures)

She goes on to become his student, lover and eventually colleague - so there's some massive character development for Spielrein.

The doctor sets about treating Spielrein for hysteria using the methods of his mentor Dr. Sigmund Freud (Viggo Mortensen) - but a rivalry later emerges between the doctors over the intriguing patient.

The synopsis for A Dangerous Method describes it as 'a look at how the intense relationship between Carl Jung and Sigmund Freud gives birth to psychoanalysis'.

Take a look at the trailer here:

One major vein of the plot is how trauma and sexuality are linked, and it emerges that Spielrein's condition was brought on by the humiliation and sexual arousal she felt when she was a child when she was spanked naked by her father.

This obviously rears its head when she's the subject of Jung's psychoanalysis studies and at one point in the film, she asks the boffin to 'punish her' by giving her a whack on the backside.

As you can imagine, Knightley had to get herself into quite the compromising position while shooting this with her on-screen love interest Fassbender - and the thought of shooting it nearly caused her to turn down the gig.

The actress explained that although she found the script 'fascinating' and she was very keen to work alongside director David Cronenberg, the spanking scenes really made her reconsider the job.

The actress starred opposite Michael Fassbender in the 2011 historical drama (Universal Pictures)

Speaking to the Hollywood Reporter in 2011, Knightley explained: "I read those two scenes and just went, ‘I don’t think that I can do that,’ particularly because it’s the age of the internet.

"It’s gonna be everywhere; I don’t want that out there...I phoned him [Cronenberg] up to turn it down.

"I said to him, ‘Look, I love you, I love the script, I love the character, but I really don’t know that I can play those scenes."

However, the director explained to Knightley that the scenes were going to be 'clinical' rather than 'sexy' or 'voyeuristic in that way'.

"And I thought, ‘Okay, well I can understand that'," Knightley continued. "As long as it’s clinical and it’s not some sort of weird, sexy spanking thing."

Knightley revealed she did some vodka shots before shooting the spanking scenes (Universal Pictures)

The 39-year-old then went on to reveal that she issued a stark warning to Fassbender before filming took place, as well as necking a few shots to brace herself for the spanking scene.

Divulging some behind the scenes secrets of how they shot them, Knightley said: "There was a box which he hit, so he was nowhere near me, thank God!

"I did actually say to Michael before one of the scenes...I was like, ‘I’ve got a security guard outside - you touch me and he’s gonna break your legs!’ And he was like, ‘Keira, you’re tied to a bed. You’re not really in a position to say that'.

"I said, ‘I guess you’re right.’… [I did] a couple of shots of vodka - definitely - beforehand, and then a couple of glasses of champagne as a celebration of never having to do that again!"

Whatever works for you, girl.