You would think there's enough pressure involved with playing the main character in the new movie from the Coen Brothers, but for Oscar Isaac, the star of "Inside Llewyn Davis," acting for the revered duo was just half of the equation.

As Llewyn Davis himself, Isaac needed to pass as a musician from the Greenwich Village folk scene in both his words and his music. When MTV News spoke with Isaac for our Fall Movie Preview, he recalled the intense shoot, the emotional musical performances, and his collaborations with his co-stars, including Justin Timberlake.

When Isaac first went out for the role of the down-on-his luck folk musician, he knew that music would be a big part of the performance, so instead of preparing the one requested song for the audition, he played three songs by Dave Van Ronk, who served as a big inspiration for Llewyn. Once onboard, he worked closely with Joel and Ethan Coen and T Bone Burnett, who is supervising the music of the film, to create both a character and a sound that felt authentic.

A quick look at the liner notes for the "Inside Llewyn Davis" soundtrack will give you an idea of the level of collaboration that went into making the movie sing. Isaac shares song credits with names a varied as Marcus Mumford, "Girls" breakout Adam Driver, and Timberlake.

Isaac explained that recording music with his co-stars added another layer of complexity to the work and forced more honesty to come through everything that they delivered for the camera.

"I guess you could say there is a level less of artifice, but it's similar as far as you're taking the existing material, whether it's lyrics or music or chords and finding your personal way into them, at the same time, my authentic voice, but also true to the character of Llewyn, who we're figuring out who he was," he said. "That had its own particular challenges. It wasn't just us getting up and singing some songs. That's not my style of playing. There's the life of Llewyn in it."

When it came to Timberlake, Isaac couldn't help but be in awe of the talent that the pop star brought to the table. "He's a huge pop star and a great writer and an incredible singer. His range is really spectacular," Isaac said. "He and Marcus actually sing bass on this a cappella song called 'The Auld Triangle.' He threw himself, with this whole enthusiasm, into it. It was a similar situation; he sang some songs in it, but he did it through the character of Jim Berkey, the mixture of creating a character and creating the music."

"Inside Llewyn Davis" opens in limited release on December 6 and goes wide on December 20.

From "Romeo and Juliet" to "Ender's Game," "Riddick" to "Oldboy," the MTV Movies team is delving into the hottest upcoming flicks in our 2013 Fall Movie Preview. Check back daily for exclusive clips, photos and interviews with the films' biggest stars.