ne he and Jack have where Leo has to prove he isn't a rat, only, of course, he is," the director says. "We shot it with double cameras, one on Leo, one on Jack and basically it is one long take. Watching the two of them together, playing off each other was one of the best things I have seen, ever."

Much has been made of Scorsese's attachment to DiCaprio, whom many critics see taking on the role Robert De Niro once had -- a combination collaborator and male muse. DiCaprio will admit nothing of the kind, not even that he has become one of the director's go-to guys.

"There is a certain familiarity of working with people you've worked with before, and I trust Scorsese, which makes my job easier," he says. "... One of the reasons I am such a Scorsese fan is that he has such respect for the people he puts up on screen. He wants the characters to be as important as the construct of the film."

Scorsese, in turn, is just as complimentary. That people were surprised when he tapped an actor who seemed terminally youthful was something that never occurred to him.

"It's true that our relationship is different because there's a 30-year age difference," he says. "... But I always just looked at Leo as a terrific actor. I was not encumbered by anything else."

He describes a scene in which DiCaprio's character must react to the violent death of another character. "It was a terrible day. We had weather problems, we had scheduling problems, and so the first take, the camera pans his face, OK, and then the second take, something clicks and what he found touched me," Scorsese says. "It was a very emotional moment. The second take. I'm ready to go four, six, eight takes, he gets it on the second take."

"Sometimes," he adds, "you do pictures all these years, you get tired. You think, 'Why am I still doing this?' Then you get a moment like that."

For DiCaprio, moments like those are more promises than reaffirmation. He is seeing a wider range of roles than he did five years ago, he says, but asked if he is still having fun, he grimaces.

"Fun? No, that wouldn't be the word I'd use," he says. "There is a satisfaction when you see what you've done and it's good."

In "Blood Diamond," he found an intersection between passions -- acting and activism. DiCaprio was drawn to the story's political backdrop as much as he was to the character and the suspense. He was deeply affected by the months he spent in Mozambique and South Africa, where the exuberance of the human spirit contrasts with the coldness of the corporate soul.

"Every problem in the world comes down to economics," he says. "In Africa you see what happens to a country when a corporation has an interest in a natural resource, like diamonds, how there has to be a social conscience at work as well."

DiCaprio spent nearly a month in Africa preparing for the role, learning the various dialects, the accents, how to handle the weapons. Then the shoot began and went on for five more months.

"It was difficult circumstances," Zwick says. "We were in challenging places -- Mozambique is not Toronto. It isn't even Romania."

DiCaprio shrugs off the physical difficulty of the location work. For him, the stress was what the stress always is -- finding the character and taking it as far as it can go. "It's like all your senses are heightened and you're thinking about everything all the time: Is the accent right, is my body doing the right thing, am I saying the lines the way I want them to sound?"

He pauses and shrugs as if he thinks he has let himself get a bit carried away with the actor thing.

"See, again, that is why I can't imagine being a director. They have all that times 10. And it's true when you meet them in the real world, they are completely different than when they are on the set.

"But then," he adds, with a sidelong glance at the ground, "I guess, so am I."