Portman, who played Nina, a ballerina descending into obsession and madness, shared how Kunis ended up landing the role of Lily, Nina’s enigmatic rival. The casting, it turns out, stemmed from a casual conversation between longtime friends.

Darren Aronofsky recalled unsuccessfully trying to start a feud between Natalie Portman and Mila Kunis to ramp up the onscreen tension in 'Black Swan': 'They're both very clever and were instantly privy.