Mark Wahlberg really throws down in 'The Fighter'

Mark Wahlberg packs quite a punch as boxer "Irish" Mickey Ward in "The Fighter" – and we're not just talking about his critically acclaimed performance. According to the actor, those on-screen sparring scenes were the real deal.

"I was really hitting people and they hit back. Hard," Wahlberg tells the Hollywood Reporter. "This wasn't a stylized fight. It was real boxing."

Indeed, Wahlberg – who plays a troubled boxer attempting to become the world's lightweight champion – spent four years prepping for the role, even building a boxing ring in his home and training 8 to 10 hours a day.

"You have to make it real," explains the 39-year-old actor, who also shared with the Hollywood Reporter his key to delivering a knockout film fight.

"The real secret in doing a scene where I was hit in the face was to make sure it was the last shot of the day," Wahlberg said.