KEIRA Knightley has revealed the amazing X-rated way she prepared for her racy new film role.
In A Dangerous Method she plays young psychiatric patient Sabina Spielrein, who gets a sexual thrill from being spanked, reports The Sun.
And to get into character, Knightley sat in front of a mirror practising facial movements that Sabina would use during solo sex acts.
She then repeated the expressions on camera for director David Cronenberg over Skype.
She says: "It was a huge part of what Sabina was doing a lot of the time. So I asked psychoanalysts about it and they said, 'Sex and anything like that is trying to release energy, trying to release pent-up emotion'.
"So I worked with that and sat in my bathroom and pulled faces at myself for about two days, trying to figure out what it was going to be.
"Then I got on Skype with David and went, 'I've come up with this', or, 'I've come up with this', and he went, 'That one!' "
The film is based on the true story of Sabina, who formed a sado-masochistic relationship with her famous shrink Carl Jung, the 20th-century Swiss psychiatrist regarded as the founder of modern psychology.