After pirouetting for hours on the set of "Black Swan," Natalie Portman would sometimes remove her pointe shoes, towel the sweat off of her brow and be met by a disapproving critique from director Darren Aronofsky.
"He'd say, 'Oh, Mila is doing really well on her stuff. She's so much better than you,'" the 29-year-old actress said, referring to her costar, Mila Kunis. "Darren would tell us things about each other to try to make us jealous. I think he was trying to create a rivalry in real life between us."
That Aronofsky may have tried to stoke competition between his lead actresses is understandable — envy is at the core of "Black Swan," a mystical ballet thriller in theaters Friday about an uptight dancer named Nina (Portman) who becomes obsessed by the threat posed by blithe new company member Lily (Kunis). The young women are vying for the lead role in "Swan Lake," and while Nina can perfectly encapsulate the virtue of the white swan, she struggles to convey the sinister, sexual nature intrinsic to the black swan that seems to come naturally to Lily.
Although Portman and Kunis were longtime friends — they often hung out together in Los Angeles, watching "Top Chef" or sifting through vintage wares at the Rose Bowl Flea Market — the director kept the two apart for nearly the entire 42-day filming process.
"We were really great friends before production. We are really great friends now. And during production, we were working together," Kunis, 27, explained.
Aronofsky denied fueling a rivalry but said he distanced the actresses so that they couldn't discuss their respective acting approaches.
"I knew it might be really hard to keep them apart because they're friends, but I just didn't want them to know each other's motives," he said. "I didn't want them to compare notes. I wanted them to come from different places."
Aronofsky, the filmmaker behind "Requiem for a Dream" and the 2008 Mickey Rourke comeback picture " The Wrestler," had his own foes to overcome to get "Black Swan" made. He decided nearly a decade ago that he wanted to do a film about the ballet world, but several ideas and scripts bogged down in development and the project lost and regained financing numerous times.
The director first met with Portman when she was 20. She had taken ballet classes as a girl and had always imagined she'd be a dancer if she weren't an actress, so she was struck by Aronofky's idea. As "Black Swan" remained in limbo, she acted in other movies, such as Zach Braff's "Garden State" and two "Star Wars" films.
While Portman was long slated for the movie, Kunis (best known for her role on the long-running sitcom "That '70s Show") was brought in only months before production began. Portman, who knew that Kunis had dance experience, recommended her friend to Aronofsky. He had seen Kunis in "Forgetting Sarah Marshall," and the two met via iChat. A few online video conversations later, he had hired her.
But from that point forward, the actresses had little interaction. Their lack of conversation is particularly interesting, considering they largely play the same character for much of the film. As Nina becomes paranoid about Lily stealing her role, she begins to have delusions — sometimes she believes she's looking at Lily, only to realize she's visualizing a darker and more liberated version of herself. The fluidity of that relationship culminates in a heated sex scene between the young women, which is teased in the movie's trailer and has for months been the subject of media fascination.
It was one of the few scenes the actresses shot together, and Portman — whose character also masturbates in the film — described it as "super awkward."
"I remember the first time we did it, we were both sort of embarrassed and not going for it," she said, sipping vegetable broth at the Polo Lounge in Beverly Hills. "And Darren was like, 'Listen. If you go for it, you're not going to have to do it again. If you get all embarrassed and hesitate, you're gonna have to do it 400 times.'"
Kunis said Aronofsky promised the actresses the film wouldn't leave his hands until it was released so that the scene wouldn't go viral on the Internet. Crew members had their cellphones confiscated so that they couldn't take any photos of the steamy segment.
Meanwhile, Kunis, who with the rest of the "Black Swan" cast has spent the last couple of weeks promoting the film, said she was irritated that she had received so many questions about the racy moment.
"How people walk away from a movie like this and the first question out of their mouth is 'Is it uncomfortable making out with your friend Natalie?' — it's unfortunate," she said in a separate interview a few days later. Reporters have also been asking both Kunis and Portman about their trysts in their next films, which are strikingly similar, centering on women in casual relationships. (Kunis is starring in "Friends With Benefits," while Portman is in "No Strings Attached.")