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.
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"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: