Robert De Niro was brought to tears during Monday's episode of "Katie."
After listening to "Silver Linings Playbook" director David O. Russell discuss his son -- who has a mood disorder similar to that of the character Bradley Cooper plays -- and his impact on the film, Katie Couric asked De Niro if he felt any greater responsibility doing a film that his director had so much personally invested in.
"Oh, of course," he answered before cutting himself off as his emotions began to show.
"I don't like to get emotional," he choked out. "But I know exactly what he's going through."
He didn't elaborate how, but Russell quickly jumped in to continue the conversation.
"When I first was in his apartment and I was talking to him about the screenplay, this is what happened," Russell explained as De Niro wiped his eyes. "I thought he was having hay fever and I realized he was having an emotional reaction. I sat there and I watched Robert De Niro cry for 10 minutes."
Watch the moment: