The pair first teamed up on the set of the 2011 thriller, and when De Niro signed on to play Pat Sr. in David O. Russell's latest project, he begged producers to cast Cooper as his son.
But the 37 year old confesses he was initially hesitant to take on the part in the Oscars favourite - even though his character is from Philadephia, Pennsylvania and loves the city's American football team the Eagles, just like him.
During an appearance on U.S. breakfast show Today on Tuesday (13Nov12), Cooper said, "He (De Niro) kind of championed me to get the role... I'm from Philadelphia, I'm Italian American, I love the Eagles... and yet I was still, 'Oh this role isn't right for me.' I was scared because David O. Russell shoots movies where you have to really do it. And it was demanding. And Bob said, 'Just don't worry about it.'"
And Cooper is glad he did the film because he got to spend more time with his friend and mentor.
He added, "I do seek his advice a lot... The guy has been in the business for 40 years and attacks it with the same voracity and enjoyment that I still do. And besides that, he's just a great human being. He's a family man, I love his morals, I love the way he walks through life. He's a superior human being."