Harvey Keitel has worked with auteurs from Martin Scor-sese to Quentin Tarantino, so he had years of research in his pocket when he was cast as a film director in Paolo Sorrentino’s “Youth.” The movie co-stars Michael Caine as a famous conductor; the two play old friends vacationing at a spa in the Alps.

Did you know Sorrentino before signing onto “Youth”?

I knew his work. I loved “The Great Beauty” and “Il Divo.” When “The Great Beauty” won best foreign language film at the Oscars, I said, “It didn’t deserve it.” People would look at me, and I’d say, “It deserved to be called best picture.” … I was not the first choice (for “Youth.”) But my agent stayed in there and got me the part.

Do you remember the last time you had to audition?

Frankly, I like to hold myself open for auditions. I want someone when they hire me to be sure they want me. And the best way to do that is if they’ve seen my work. If they have not, I’m willing to read for the part.

It’s hard to believe that you’ve never worked with Michael Caine before this movie.

People say that; it’s interesting. Michael’s an actor I’ve always admired. He’s one of those actors who set a standard for the work when I was a young actor. I’m so happy to get the chance to work with him.

What do you think was the secret to your chemistry?

We like to kid around in that we both have a similar background; he was in the British Army, and I was in the Marine Corps. We understand each other.

What’s the best advice you could offer a young actor about their career? 

Be careful about choices, if you’re lucky enough to have them. Because young actors don’t like to think about Hollywood being a business; you just want to go, go. But you must leave space in a part of your brain for the business.

Your career began in theater; how long has it been since you’ve been on stage?

I’m very eager now to do a play again. I’m looking for one. I remember Israel Horovitz writing a play, and he asked me to do it. I was dying to do it, but I kept laughing too much! He kept telling me to stop laughing, and I couldn’t.