When an actor wants to convincingly play a boxing champ on screen, he's got to go directly to the source. And that means bringing on a real former champ as a consultant. It's his job to make sure the actor stands, moves, and, most of all, punches like a true fighter.

As the boxing consultant for the upcoming movie "Real Steel," former world champion Sugar Ray Leonard had a unique challenge. Not only did he need to make star Hugh Jackman look like an actual boxer, Leonard was also responsible for showing 8-foot-tall, 2000 lbs. robots how to fight, too.

The movie takes place in the near future, where human-controlled robots have taken over the sport of boxing. Jackman plays Charlie Kenton, a one-time contender who's now just scraping by with shoddy robots in underground fights. But with the help of his son, Charlie trains a rescued robot and turns it into a potential champ.

The film's director, Shawn Levy, told the Wall Street Journal he was looking for a boxing consultant for two reasons: "To vet the story, and just as importantly, to work with Hugh on the mindset of being a former boxer." And few others have the credentials of Sugar Ray Leonard. He was an Olympic gold medalist; he won world championships in five weight classes; and he was inducted into the International Boxing Hall of Fame.

"I worked with Hugh on proper execution of punches and the emotional content between the boxer and the trainer," Leonard told Yahoo! Movies in an email interview.

The former champ stressed the importance of eye contact and focus, which was a particular challenge since Jackman was working with actual, life-size animatronic robots in addition to entirely computer-generated characters.

The filmmakers also used Leonard's expertise to make the boxing scenes as real as possible. They used boxers with motion capture suits to create the fights, and the director and Leonard were able to actually see on a monitor how the robots would interact in real time. Jackman told WSJ.com, "We have 20 robots and each has to be incredibly distinct, and he really gave them all signature moves."

Leonard said that the problem with most boxing movies is "they leave out the execution of throwing proper punches. It doesn't appear very real without this execution." Since this movie is already dealing with the fantastical concept of oversized robots battling each other, it became all the more necessary for the boxing action to feel legitimate. Leonard concluded, "There are ways to sensationalize the punches for the movie but there are still other ways to make it look real."

Leonard had high praise for the movie's star, saying "Hugh ... has a great passion for the sport of boxing." But when I asked if Jackman could have stood a chance in the ring against Leonard in his prime, he answered with an unequivocal "No."

The film opens October 7.

Sugar Ray Leonard's new book, The Big Fight, is available for pre-order here.