Sebastian Stan realised 'I, Tonya' was a special movie during his time on set.

Sebastian Stan

Sebastian Stan

The 35-year-old actor stars as Jeff Gillooly, the ex-husband of controversial American figure skater Tonya Harding, in the new Craig Gillespie-directed film, and Sebastian feels the hard work and patience of the cast has paid off with the positive feedback they've already received.

Asked when he realised he was making a special movie, Sebastian shared: "It was definitely on set. I mean, the movie kind of came together there and we knew because the days were really long ... 31 days to shoot it.

"And there were all these skating sequences and it was a lot to get done."

But Sebastian said that because the cast - which also included Australian star Margot Robbie - were aware of how good the film could become, they never lost patience with the director.

Speaking to Collider, Sebastian explained: "We never got frustrated because everyone was operating from a point of view of what was the creatively most important decision that we could make on that day.

"For the film, for the story ... it's what shot really needed to be in the movie."

Meanwhile, Margot recently admitted she didn't know 'I, Tonya' was based on a real-life story.

The blonde beauty plays Tonya - who pleaded guilty to hindering the prosecution following an attack on her rival Nancy Kerrigan in 1994 - in the film, but she was initially unaware of the dramatic storyline.

Margot confessed: "I didn't realise it was a true story.

"I thought it was complete fiction, just a wacky story. And then I found out it was all true and I was even more fascinated."