,Michael Bay was star's biggest challenge on 'Transformers' Gibson said on a recent visit to Toronto

Working with Michael Bay's "Transformers" franchise has been "the hardest part of the job and the best part," says Tyrese Gibson, who plays Tech Sgt. Epps in the series.

"Michael's demanding," Gibson said on a recent visit to Toronto. "He makes you go through hoops until the job's done right. But when you hear him say 'Good job, man,' it means something."

Director Bay created the role of the tough combat sergeant for Gibson after seeing him star in John Singleton's 2001 film, "Baby Boy," and the 2003 action flick, "2 Fast 2 Furious."

Prior to these films, Gibson was known as a model and R&B singer.

Now Gibson and Shia LaBeouf return in "Transformers: Dark of the Moon," the third entry of a franchise that has so far earned US$1.5 billion.

True to its roots, "Transformers 3" is full of shiny metal robots, daredevil stunts and ear-piercing explosions.

It's got a new love interest for LaBeouf's hero, played by Victoria's Secret model Rosie Huntington-Whiteley.

The film's script written by Ehren Kruger also puts an intriguing fictional spin on space history.

As the story unfolds, a mysterious alien spacecraft crashes onto Earth's moon. That event turns NASA's 1969 moon landing into a covert investigation of the wrecked spacecraft. And NASA isn't the only party interested in the vessel.

"Transformers'" good-guy Autobots and evil Decepticons also get in on the hunt. The warring robots race to retrieve the spacecraft and it secrets.

"This new story is a game-changer," said Gibson.

"Frankly, I was worried that we wouldn't be able to top the action of 'Transformers 2.' But we did and delivered a strong story," he said.

Hopefully movie critics will agree.

"Transformers" 1 and 2 were panned by critics. To them Gibson has offered this advice: "Get over it."

"At the end of the day, fans like the escapism. It's just good fun. The critics should remember that," said Gibson.

This year Gibson starred in the surprise hit, "Fast Five." He also published his first memoir: "How to Get Out of Your Own Way." The bestseller documents Gibson's rise from poverty and violence in L.A.'s Watts neighbourhood.

"‘Transformers' opened many doors for me. I learned a lot from Michael and my colleagues," said Gibson.

That includes former ‘Transformers" beauty, Megan Fox.

"I was genuinely sorry when I learned that Megan wouldn't be in ‘Transformers 3,'" said Gibson.

The actress with the ice-blue eyes and killer body played LaBeouf's love interest, Mikaela.

The character was dropped from "Transformers 3." Many believe the cut was made after Fox made critical remarks about Bay.

"There is only one Megan Fox," said Gibson.

"Rosie isn't replacing Megan. She's playing a whole new character," he said.

"Is she hotter than Megan? Is she better? Fans will compare. But I don't think you can."