Canadian actress and director Sarah Polley said she had no second thoughts about casting two off-the-wall comedians in her new drama Take This Waltz.

In fact, she was surprised how smoothly performers Seth Rogen, known for The 40-year-old Virgin and Knocked Up, and Sarah Silverman, of The Sarah Silverman Program, adapted to the script.

“When I look at the actors here, I realized that each one of them I was always a huge fan of, but I had never seen them play a role quite like this. So it was also a selfish thing, as a fan, to want to see Seth and Sarah play dramatic roles,” said Toronto-based filmmaker Polley.

“It doesn’t seem like a different process to me and there is an authenticity and honesty and bravery in their work that just translates so obviously and naturally to dramatic roles. It was so thrilling to see that and to totally exceed my expectations of the performances."

The drama, which takes the title from the work of Canadian poet and singer-songwriter Leonard Cohen, revolves around the life of 28-year-old Margot (two-time Academy Award–nominee Michelle Williams), who is married to Lou (Rogen), a cookbook author.

But when Margot meets a neighbour named Daniel (Luke Kirby), their mutual attraction is almost immediate. This tangled relationship leads her to question the value and sustainability of long-term relationships and causes her to struggle to choose between her husband and a man she's just met.

The film marks Polley’s return to directing with her first feature since 2006 festival favourite Away from Her.

Canadian director Sarah Polley, at right, defended the use of comedians Sarah Silverman, left, and Seth Rogen in her latest film Take This Waltz. The Associated Press

“It is something to talk about when a dramatic actor can go and do comedy, that’s really impressive,” said Polley. “I think it’s less shocking when a great comedian does a great dramatic role…I was amazed at how surprised that people would be that that would have worked.”

Silverman, who plays Lou’s foul-mouthed sister Geraldine, said she felt some honesty in delivering dramatic lines.

“I feel like in comedy you can be saying a bunch of lies, but the audience smells b---s--- if there isn’t some sort of honesty coming through in this,” she said. “It’s like saying words honestly, it doesn’t really feel so different.”

Rogen concurred, noting that “a lot of people have been talking to me about how it is totally different from what I have done before, but it doesn’t feel different from anything.”