TORONTO - Matt Damon's comedic turn as an agri-business executive who goes to the FBI with the inside scoop on his employer's criminal wrongdoing definitely isn't your "father's whistleblower movie."

After all, tales of true-life corporate crime are rarely rolled out as comedies.

"The Informant!" follows the exploits of Mark Whitacre, who in the 1990s helped expose his company's involvement in a global price-fixing scheme involving animal feed. It's based on a non-fiction book that director Steven Soderbergh decided should play onscreen as a comedy, a choice both the star and director knew would be a challenge.

"(Soderbergh) called me up and said, 'Look, "The Insider"'s made - that movie's great, we just can't go ape (it),' " Damon said in an interview at the Toronto International Film Festival, referring to the 1999 film about the tobacco industry.

Soderbergh wanted to do something different, more of a comedy, Damon said.

"You're aiming at a smaller target with that tone, and you need a director who is just on it, because it's all down to him."

That approach gives "The Informant!" a unique feel that Soderbergh concedes may have left test audiences somewhat confused.

"I thought, people just aren't getting that it's OK to laugh," the amiable director said during a separate interview, in which he volunteered that test scores from all three screenings came in at a "terrible" 55.

"This is not 'The Insider.' This is not your father's whistleblower movie."

Turning Whitacre's story into a comedy could not have been "further from our minds" when the rights to Kurt Eichenwald's book were secured, Soderbergh said.

"It really was by defining what we didn't want it to be that we came to find out what it ought to be," he said.

"It seemed to have one of the best building blocks for a comedy that you can have, which is the lie that escalates. There's a lot of classic comedies that use that as their premise."

Soderbergh is known for blockbusters like "Ocean's Eleven," its sequels and the critically acclaimed "Traffic," which won four Oscars. He also has a reputation for experimentation in such films as "Full Frontal" and "The Girlfriend Experience."

Damon, who also starred in the "Ocean's" films, said he has complete trust in Soderbergh's instincts.

"It was just having somebody there the entire time who I trust implicitly, creatively, so I can allow myself to go in all these different directions and know he's there, and he'll always shepherd me back onto the right path," he said.

"When you feel like you're in such sure hands it becomes really fun to work."

Damon, the bankable star of the "Bourne" trilogy, said that since Soderbergh made the film for just $22 million they were free to take whatever approach they wanted.

"Tonally this movie is unique, so you want to be left alone," Damon said.

Melanie Lynskey, who plays Whitacre's wife, said working with Soderbergh was beyond her "wildest dreams."

"My friend was actually casting the movie and said 'You know, you'd be so great for this part.' I'm like, 'Yeah, I'm really going to get that part of Matt Damon's wife in a Steven Soderbergh movie,' " she said.

Apparently the director didn't want to populate the supporting cast with "famous" people, said Lynskey, best known for playing Rose on TV's "Two and a Half Men."

"That works for me. It's like the only time in my career that that's been a positive thing."

While Damon's name is internationally known, the star left his famous physique at the door. He put on some 30 pounds of pudge for the role.

"It was really great. I didn't stop eating for two months," he said.

"If I didn't have food, someone would hand me a bag of Doritos."

"The Informant!" opens in Canadian theatres Friday.

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