ROSAMUND PIKE COVERS VANITY FAIR MAGAZINE SHOT GONE GIRL SEX SCENE WITH NEIL PATRICK HARRIS 36 TIMES

If you cringed in Gone Girl during Rosamund Pike (Amy Dunne) and Neil Patrick Harris' (Desi Collings) disturbingly violent sex scene, just imagine what it was like filming the bloody thing!

Director David Fincher tells Vanity Fair's February issue that Pike and Harris had to shoot that particular scene 36 times. "I told them to rehearse it for three days," he explains, "as we're pumping five gallons of blood out of

Desi's throat." They finally filmed the gruesome R-rated interchange with "36 sheets, 450 gallons of blood and 36 pairs of underpants" on hand, says Fincher.

Pike admits, too, that filming for Gone Girl was tough. "I spent more time in front of the camera on that film than in my entire career to date," the 35-year-old actress tells Vanity Fair, "because he's [Fincher] shooting five to six hours of footage a day, and over a hundred days shooting--that mounts up."Even so, she says when it comes to her next role, what she'd "really like is for David Fincher to just ring up and say, 'Are you ready for Round Two?'"

Part of why Fincher cast Pike opposite Ben Affleck in the flick is that at the time, she was relatively unknown in America. Even now, there's a bit of mystery to her--something her Pride and Prejudice co-star Carey Mulligan admires. "What I love is that people don't know [Rosamund]," Mulligan tells Vanity Fair. "She chooses not to let people know about her personal life. She promotes the work and that gives her such integrity. She's completely free of associations to other things when she's in a role."The mother of two does, indeed, try to keep her private life out of the spotlight. She rarely speaks about her partner Robie Uniacke, a man she describes as "the most interesting person" she's ever met." Uniacke, who is 18 years older than Pike, is  a "clever partner who's got a very astute mind and is very, very well read and articulate," she says.

He avoids the pitfalls of fame, too, it would seem. As Pike tells Vanity Fair, "The quality I most admire about him is he sees the value in anonymity."

For Pike's full interview, pick up the February issue of Vanity Fair.