The actors discuss working with Martin Scorsese and Jack Nicholson

Leonardo DiCaprio and Matt Damon co-star in director Martin Scorsese's gangster thriller, The Departed. The film is an adaptation of the Hong Kong cult classic, Infernal Affairs. The actors play cops with very different agendas. DiCaprio stars as Billy Costigan, a new recruit that is sent undercover into the sordid world of crime boss Frank Costello (Jack Nicholson). Matt Damon stars as Colin Sullivan, a cop working for Frank Costello inside the police organized crime unit. Both men play a dangerous game of cat and mouse, informing on their superiors while hiding their true loyalties. The Departed is the third collaboration in a row for DiCaprio and Scorsese.

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Brad Pitt produced the film along with Graham King. Did his involvement spur you both to participate?

Matt Damon: Brad, Leo, and I were in a bathhouse together. I think the moment these things are born. I have to say what happened. (laughs) No, Brad came to me because his company had access and I first heard about it through Brad. It's like the dream of all dreams. Hey, did you hear that Martin Scorsese is directing a movie about Boston. For me that was it, really. Then I got a copy of the script, loved it, and when I came back to New York, I met with Marty. But I think I had already agreed to do it, it was a really easy yes for me.

Leonardo DiCaprio: I never had an initial conversation with Brad. I got the script around when Marty got the script. Bill Moynihan's work here, this tightly woven, highly complex ensemble piece, this gangster thriller; it's very, very rare in this business where a script lands on your lap ready to go. This was one of those rare occurrences. Marty and I just talked to each other. It was one of those things that we really didn't need to discuss. He really wanted to do it. I really wanted to do it. And for a lack of a better term, the rest is history.

How did you decide which characters to play? They are both very different, but are essentially stuck in the same situation?

Matt Damon: We actually did flip a coin. That was how we decided. No, speaking for Leo (laughs), I think we would have been happy to play either one. We're happy that that's the way it turned out, because I can't imagine playing the other one now. It's really rare in a film of this budget to have characters this interesting. Generally, the bigger the budget, the less interesting the characters become. All of us had great things to play, so that's a real credit to Bill Moynihan and his script to be able to have that much to do when you go to work everyday.

Leonardo DiCaprio: I agree with Matt 100%, these characters are two sides of the same coin in a lot of ways. They come from different backgrounds, but they could have easily made choices the other character made. It just sort of happened that way. I don't know. I suppose Marty and I got the script first, and Matt was the next guy onboard. It was ultimately Marty's decision at the end of the day.

How did you both prepare to play these roles?

Leonardo DiCaprio: I guess by watching Martin Scorsese movies, right? (laughs) It's not really familiar to me, that form of immediate violence, but that's what you do as an actor. If you can't draw upon anything in your real life, you go meet people that have done these sorts of things and part of the process for me was going to Boston. I had never spent any time there. Sort of learning about the Boston subculture, meeting some of the real people who were around during the late '80s, the whitey era, we may call it, but I really wanted to meet some guys from south Boston. I met a guy in Los Angeles and spent a lot of time with him. He told me a lot of stories about the streets there and Boston's a really interesting place because everyone knows each other's business. It's like a little microcosm there and everyone waves to each other on the street. We shot a lot of it in New York. We should have shot some of it in Boston. It was very important to meet some of the real characters and get to know them and hear some stories. You can read books and I read a few books, but to be able to penetrate some of these guys, their minds, and really get deep into what they were thinking was important. We had a great technical advisor named Tom Duffy who was there throughout the entire filmmaking process. He knew the entire history of Boston and knew what the streets were like. The police also gave us unbelievable advice. Matt actually went on a raid in a crack house.

Matt Damon: Yeah, have you ever seen the movie "The Hard Way" with Michael J. Fox? That was me. Hey guys, I get a gun? They're like absolutely not, shut up. As Leo said, Tom Duffy was a huge resource. Duff was able to get me around a bunch of police. It was really fascinating. I had a real advantage because I'm from Boston, so I didn't have to learn an accent or do anything like that. I got to get straight to investigating this sort of subculture of state police. I spent a lot of time with these guys just sucking it in, not really having to have a goal but just sitting there and spending time. For instance, this raid on the crack house, I'm sure I was in no real danger, but they brought twice as many cops as they usually do. I was in the back of the line, so I had my bullet-proof vest on, standing there going, what am I doing here? I didn't go in until they cleared the house, but I got to see them do it. Marty's really insistent on authenticity. He uses a lot of real people and because his actors have access to these real people, they get as much understanding of the people that they're playing. We're just trying to be believable. If you're taken out of the movie at all, then we haven't done our job right.

Were you at all familiar with Infernal Affairs, the Hong Kong classic The Departed is based on?

Leonardo DiCaprio: We all watched it. And we all enjoyed the film, but I think we had to separate ourselves from it to a certain extent. Certainly the construct and the skeleton of the story is very similar in this version, but it's dealing with an entirely different underworld. It's dealing with Irish-Americans in Boston. We also had to forget a lot of those elements because we knew that we had to invent an entirely different film.

Matt Damon: I loved the Hong Kong film. I thought it was fantastic. And I loved those Hong Kong actors, but it's about such a different culture. Boston is different even from any city here in America. The world that Bill [Moynihan, the screenwriter] built around it was very specific to Boston.

What was it like working opposite Jack Nicholson?

Matt Damon: We have a lot of Jack stories. The first day I worked with him, he had been working with Leo for about a week. I get a phone call. "Hi, Matt? Marty, the director." I love that he always says Marty the Director. He said, "Well, a funny thing has happened, Jack had some ideas for your scene tomorrow." We were shooting a scene in a movie theatre. " Jack's going to wear a dildo." So we went in the next day and rehearsed it. Jack's idea was like, (in Jack Nicholson voice) "I'm gonna come in, I'm gonna sit there in the overcoat, and I'm gonna pull out the big dildo and we're gonna laugh." Jack really brought this incredible new element that felt authentic. It felt like these guys really would sublimate sex into violence and violence into sex, and it really is how a lot of those things did occur. I don't know how much research he did or how much he just intuited or what his process was exactly, but I found him really committed to making the thing as believable and pushing the envelope as much as he could.

Leonardo DiCaprio: As far as Jack was concerned, we kind of expected the unexpected. We knew that if he was going to come, to have Jack Nicholson join up with Martin Scorsese and play a gangster is something that I think a lot of movie fans have been waiting for. For me, there were a number of different scenes where I had no idea what was going to happen. I remember coming in one day and the prop guy told me to be careful, he's got a fire extinguisher, a gun, some matches, and a bottle of whiskey. I think we all knew that if he came on board, that he would have to sort of grab the reins with this character and let him be free form. We all were completely ready for that every day that we walked on the set. He had a short run. He filmed his scenes and then he left, but those were some of the most intense moments of the film for me certainly and as a human being. Those were some memories that I will never forget.

Leo, what is it about Scorsese as a director and a person that attracts you to his films?

Leonardo DiCaprio: I'm a fan of his work, number one. I suppose for me that it all started during "This Boy's Life" with Robert DeNiro and getting sort of familiar with Robert DeNiro's work, and obviously that means Martin Scorsese's work as well. So I became a fan of his work at a very early age. If you asked me who I wanted to work with starting out in the business, it would have been him, and I got fortunate enough to work with him on Gangs of New York in 2000. I don't have an exciting term for it other than we have a good time working together and we have similar tastes as far as the films we like. He certainly has broadened my spectrum as far as the history of cinema and the importance of cinema. It really brought me to different levels as an actor. I look at him as a mentor.

The Departed is in theaters this Friday and is rated 'R' for strong brutal violence, pervasive language, some strong sexual content and drug material.