Sylvester Stallone was the "alpha wolf" on the set of The Expendables 2.

The sequel to the 2010 blockbuster hit sees a number of heavyweight action stars duke it out, including the likes of Arnold Schwarzenegger, Jean-Claude Van Damme and Bruce Willis.

Yet despite the presence of so many big hitters director Simon West revealed that Sylvester was the most respected on set.

"With any wolf pack, there's an alpha male," he told Total Film Magazine. "No matter how tough the wolves are, there's always an alpha male. And Sly is that alpha wolf."

Dolph Lundgren plays Gunnar Jensen in the upcoming action film. The actor explained that while Sylvester was the most dominant star on set, there was no tension between the rest of the cast.

"I think we are all competitive in a lot of ways but there's a hierarchy on the film based on experience," he explained. "Nobody challenged that, or had issues with that. Stallone is heavily involved with every aspect of the film."

"Sly's the big chief, he knows what he wants," Jason Statham added.

Sylvester - who directed the first Expendables instalment - remains modest about his status on set. The 65-year-old Hollywood star suggested that he merely offers tips to the others.

"There's a lot of alphas here, no one wants to be outdone," Sylvester confessed. "They're on camera, bringing their A-game. What I can bring to the table is advice, because I wrote these characters. I can say, Try it like this..."