The muscular actor - who portrays boxer 'Irish' Mickey Ward in the movie alongside Amy as Charlene Fleming - liked her as soon as they started to work on the film because she reminded him of a prettier version of girls he knew as a child.
He said: "She's a sweetheart. The director David O. Russell always says that she doesn't seem like the girl who could throw a punch but she reminds me of so many girls in my neighbourhood.
"She looks like an Irish Catholic, tough, no nonsense kind of girl. I saw that immediately. They're not quite as pretty as Amy, the girls in my neighbourhood."
The 39-year-old star believes the drama film was a good opportunity for the flame-haired actress - known for her roles in 'Enchanted' and 'Julie and Julia' - to show a different side to her skill set.
He said: "I was very happy about that because I thought she would bring something very special to the table, and again showing a side of her that I certainly knew she was capable of doing but she hadn't gotten to show yet."