The career of any great movie actor often can be traced back to a single moment, or series of moments, in a single film, where the audience takes notice as a star is born.

You know what I mean: Tom Cruise sliding across the floor in "Risky Business"; Liza Minnelli exploding onto the stage in "Cabaret."

Oscar Isaac ("Drive") has a scene like that about two-thirds of the way through "Inside Llewyn Davis," the great new film from Joel and Ethan Coen.

Isaac's Llewyn Davis, a brilliant folk singer in New York City circa 1961 who simply can't find his way to professional success, performs the English ballad "The Death of Queen Jane" in a crucial audition. It's an aching, heartbreaking eruption of pain and hope; despair and passion.

amNewYork spoke with Isaac about the movie, which is in theaters now.

You're a musician and an actor and you performed the songs live here. Talk to me about that challenge.

On the practical side, actually, performing live at a show is scarier, because you only have one chance to get it right. In the film, if I f----- up, we could just do it again. ... However, you have to add the element of the camera being there and the fact that it is a crucial element to the character.

The folk style was new for you. How'd you go about learning it?

You get the script. Or the audition at least, we just got a couple of scenes. And a recording of "Hang Me," Dave Van Ronk, which I hadn't heard before. The first thing I do is fine everything that Dave Van Ronk has ever recorded and listened to. Then it was a process of listening to his type of guitar playing, listening to what it is and then deciding, I needed to record the song, so 'How am I going to do it?' It was very difficult but I had something very serendipitous and fortunate happen. I was doing a small film in Long Island. There was a guy, who was playing a featured extra, old guy at the bar, and in between takes there was a guitar lying around. He picked it up and started playing in exactly the Dave Van Ronk style.

So what happened?

He was incredible. So I went up to him and started talking to him and I said, "Wow man, you're amazing. What's your story." He said, "My name's Eric Franzen, I've been in New York forever, I'm an actor." I said, "Wow, I'm auditioning for this thing, it's loosely based on Dave Van Ronk, have you ever heard of Dave Van Ronk?" He said, "Yeah I played with Dave." I said, "Do you give guitar lessons"? He said, "Absolutely, come to my place" and I asked, "Where do you live"? And he said, "I live on MacDougal Street above the old Gaslight." ... So then, he started teaching me this style.

Is it hard to move on from a project like this, given who you worked with and the acclaim it's received?

I don't think I'll ever move on from this. It was such a seminal moment in my life and more than anything, because I developed a friendship with Joel and Ethan. They've enriched my life just with talks with them about anything. ... And my work with T-Bone [Burnett, the film's music supervisor]. He's a musical revolutionary. That was such singularity for me that it's impossible to move on. At the same time, I like to work, and so I'm interested in bringing some of what I've learned from that experience onto the next thing, but I don't know if I'll ever have something that's quite as seminal in my life as this one.