Some say that John G. Avildsen and Sylvester Stallone watched this movie in preparation to make Rocky. Stallone has admitted in an interview with Adal Ramones that he has seen it indeed.
Wolf Ruvinskis plays the role of an arrogant fighter, but in real life, he was a kind person. Joaquín Cordero, on the other hand, plays the role of a very good man, but in resl life he was arrogant and egocentric.
Wolf Ruvinskis was the only of the three main actors who had real experience as a boxer. He was a gifted athlete. In Argentina he practiced Soccer, Boxing, Grecorroman Wrest, and finally, Free Style Wrest.