With reporting by Josh Horowitz

Sometimes, when you meet someone for the first time, there's a spark. That's what happened to Tom Hiddleston and Elizabeth Olsen, at least.

The rumored couple star in the upcoming "I Saw the Light," a biopic about the rise of country singer Hank Williams, which premiered at Toronto International Film Festival this week. They've been linked throughout the summer, but Olsen told MTV News that the two had instant chemistry when they met on an audition four years ago.

"Tom and I have been wanting to work with each other for a while," she said. "We've known each other for about four years, and we met doing a chemistry read for an audition and we were like, 'oh my God, this would be so much fun if we worked with each other.'"

"I Saw the Light" happened to be the first film that was right for the duo to share the screen. Olsen opened up about what a chemistry read entails, and why hers and Tom's was so great.

"What happens is either people are so nervous that all they're thinking about is what they're doing in order to get the job, or two people are just like, 'I did the work and I guess we're trying to figure out if we have chemistry, so I'm going to put all my focus on you and listen and play.' We both, doing that to each other within the scene, the intention is always to check in on each other and measure them in a way and we were like 'oh, we'll work really well together.'"

"That's fun as an actor to find someone who you have very similar language with," she said. "So that was the impulse in 2011."

She also sang Hiddleston's praises as a lip sync artist, surprisingly enough. Olsen said that she likes to make lip sync videos for songs she loves, but that perfectionist Hiddleston goes above and beyond.

"When Tom does it, it's like a choreographed event," she said. "And it's always a mic drop."

"He's an incredibly thorough person, and I feel like when you're always that thorough you always have that expectation and other people have that expectation."