Anthony Ippolito, who stars as a young Sylvester Stallone in I Play Rocky, opened up about speaking with the action star in preparation for the biopic.

The Purple Hearts actor told The Hollywood Reporter at the Toronto International Film Festival on Saturday that talking with Stallone about his life, early career, and the development of Rocky was an “overwhelming” experience. Ippolito plays Stallone in Peter Farrelly’s I Play Rocky, which follows the tumultuous production of the 1976 boxing film that won three Oscars, including best picture.

“ I got to speak to Stallone prior to making the movie. It was a lot to take in because I’d spent over a year, by that point, studying him,” Ippolito said at THR‘s Studio at 1 Hotel during TIFF, presented by sponsor Canada Goose. “It was very overwhelming and daunting. There’s a lot going on in my head, but I was really just trying to listen as much as possible and hear his perspective. Obviously, Rocky’s an underdog story and he’s an underdog in the movie, but Stallone in a lot of ways was an underdog in his actual life.”

Ippolito revealed that he and Stallone chatted about Stallone’s early childhood and many of the difficulties he had to overcome, including paralysis of the lower left side of his face after doctors accidentally severed a nerve during childbirth. The complication gave Stallone his signature voice and look, which became famous when Rocky hit theaters in the ‘70s.