TORONTO - Canadian Sarah Polley says she completely lucked out by snagging her "favourite living performer right now" for her new movie, "Take This Waltz," which she directed last summer in Toronto.

That performer is edgy, foul-mouthed comic Sarah Silverman.

"I think she's so brave and interesting and pushes the envelope in so many ways. She's enormously political as well in ways that I don't think people give her credit for," says Polley.

Silverman is best known for her boundary-pushing humour -- which often trades on taboo subjects like religion, race and sexism -- but she shows a more serious side in "Take This Waltz," said Polley, who also wrote the screenplay for the film.

"I was just really excited to work with her. I think someone like that is so obviously deeply intelligent that they are going to give a great dramatic performance and she really did in our film."

The movie, which may hit theatres next year, is Polley's hotly anticipated followup to her 2006 directorial debut, "Away From Her," which nabbed her an Oscar nomination for best adapted screenplay.

The script, which takes its name from a Leonard Cohen song, made 2009's "Hollywood Blacklist," an annual collection of highly touted unproduced screenplays. It appeared alongside the likes of "The Social Network," "The King's Speech" and "Buried."

"Take This Waltz," also starring Michelle Williams and Seth Rogen, is the story of a woman who is tempted to stray from her marriage after a chance encounter with an intriguing man on a business trip. Things become even messier when they realize they actually live on the same street and will surely run into each other again and again.

Torontonians should have no problem recognizing their city in the film, if a script circulating online holds true.

Neighbourhoods like Little Portugal, Little Italy and Little Korea are name-checked in Polley's script, and there are references to the city's streetcars and rickshaws. One character says his biggest regret is not watching the Toronto Maple Leafs the year they went deep in the playoffs.

Scenes were also shot in Louisbourg, N.S., to depict the protagonist's business trip to Cape Breton.

Polley said the filming went smoothly and that the movie is currently in the editing stage. She's not sure when it may hit theatres.

"I don't know, sometime next year I hope," she said.