Kate Winslet revealed she and "Ammonite" co-star Saoirse Ronan took their sex scene very seriously.

So much so, the two actresses "choreographed" it themselves. Winslet explained to The Hollywood Reporter that the film's director, Francis Lee, was "nervous" about how the scene would look.

"I just said to him, 'Listen, let us work it out.' And we did," Winslet said.

'AMMONITE' TRAILER FEATURES SAOIRSE RONAN, KATE WINSLET AS PALEONTOLOGISTS FALLING IN LOVE

''We'll start here. We'll do this with the kissing, boobs, you go down there, then you do this, then you climb up here.' I mean, we marked out the beats of the scene so that we were anchored in something that just supported the narrative," the Academy Award-winner described.

In the film, which is set in the1840, Winslet plays real-life paleontologist Mary Anning, who falls in love with depressed housewife Charlotte Murchison (Ronan). The two women then begin an affair.

The "Titanic" star admitted she "felt the proudest I've ever felt doing a love scene on 'Ammonite.' And I felt by far the least self-conscious."

"I'm nearly 45, and Saoirse is almost half my age. And to have an opportunity to be my real 40-something self, post-children, you know? Women aren't really having the courage to do that," she said.

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Winslet admitted she never thought of using a body double because "this is what it is, peeps. This is how I am now,' and it's very much not the body I had 20 years ago."

Saoirse Ronan (L) and Kate Winslet (R) in 'Ammonite' 

Saoirse Ronan (L) and Kate Winslet (R) in 'Ammonite'  (Lionsgate/Neon)

She also made sure not to lose weight during the shoot.

"I hate to talk about weight, but I only say it in the context of, it was a conscious effort on my part to really make sure that I didn't shrink or change myself for the sake of being naked," Winslet said. "I did the opposite."

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"Ammonite" is set to premiere at the Toronto Film Festival. The cast will be attending virtually due to the coronavirus pandemic.