Aronofsky's next film was "Black Swan", which had been in development since 2001, a psychological thriller horror film about a New York City ballerina. The film starred actress Natalie Portman, whom Aronofsky had known since 2000. She introduced Aronofsky to Mila Kunis, who joined the cast in 2009. "Black Swan" had its world premiere as the opening film at the 67th Venice Film Festival in September 2010. It received a standing ovation whose length "Variety" said made it "one of the strongest Venice openers in recent memory".