Transcript for Mark Ruffalo on Working With Channing Tatum, Steve Carell
And fresh off his Emmy for the Normal heart, mark Ruffalo and his co-stars getting Oscar buzz for their roles in "Foxcatcher." He is caught up in the world of the eccentric multimillionaire played by Steve carell. Take a look. Hey. Really sorry about your mother. No, no, no, it's fine. Are you okay? Yes. You sure? David, we have a lot of work to do in the next couple of months. And you're an integral part of that. You understand? I understand. We're going to need you. And I will be relying on you to a great extent. I want more than anything to win a gold medal. And mark Ruffalo joins us now. Boy, that scene shows so much. You're starting to bond a little bit -- Yeah. With Mr. Dupont. But your brother. Can't quite take it. No. No, he's -- they're not doing so well at that moment. No. And you've likened this movie, which is just an amazing film, to a Greek tragedy. Yeah, I think it has that kind of sort of deep, complex, human struggle in it. That's tied up in family and ambition and success and sort of having to choose between those things. Yeah. And the character you play, Dave Schultz and his brother, both olympic gold medalists, yet both kind of struggling in life. Yes. For the U.S. Wrestling at that time in America, there was really no support for them from, you know, from the state. From the federal government. So they were really struggling to -- to go to the olympics and to maintain this level of -- of excellence for -- Which is why they got hooked up with this millionaire. What did you think when you first walked in and saw Steve carell like that? I was repulsed. I -- I was with someone who was very close to Dave Schultz, a guy named John, his best friend who was on the farm with them when this all happened, and he looked up. And he blanched. He saw Steve coming around the corner and he literally went white. I was looking, and I turned around, and there was carrell looking very much -- A stunning transformation. A career-making performance. All three of you, and Channing Tatum was here last week. You were a wrestler, he said it was the hardest thing he had done. I thought I knew what I was getting into. It was an different level. The amount of commitment. Channing and I started working out seven months before we even shot a single frame of wrestli wrestling. And I had to put on 25 pounds. And it was -- it was really challenging for both of us. But, you know, we really bonded during the course. And it really, really paid off. You have a birthday coming up. That's right. This week. And we have a special tribute for you. Take a look. Oh, no. Hi, dad. You didn't pick me up on that father-son trip. Whenever you want to call me, we can do a fishing trip or something and catch up. If you want. I miss you. Aw. Thanks, son. Kids are all right. What a great movie too. That kid's all right too. He certainly is in josh is doing so well. "Hunger games," that's great.
This transcript has been automatically generated and may not be 100% accurate.