Real or Hollywood fakery?

One of the most dramatic moments in the trailer for "The Revenant" has Leonardo DiCaprio getting attacked in the woods by a bear, which chomps on his back and leg and tosses him around.

For now the actor's remaining mum on exactly how they pulled off that scene -- whether the bear was real or CGI or a guy in a suit -- or some combination therein -- but he does offer some clues.

"Well, I’m not going to give any specifics on how we did it — you’ll figure it out on your own," he tells Yahoo. "But I will tell you it involved cables, it involved me flying around the forest, and it involved a tremendous amount of rehearsal. And it was pretty agonizing to do."

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DiCaprio says that scenes like this in the film are "some of the more difficult things I’ve ever had to do in my entire career" but insists it was worth it.

"The end result is going to be one of the most immersive experiences audiences will ever have with what it would be like to come face-to-face with an animal of that magnitude that is incredibly primal," he says. "It is absolutely startling and shocking, and it is the closest thing to documentary filmmaking — but in a completely stylized way that a lot of people never experienced."

Directed by Alejandro González Iñárritu, the actor takes on man and beast as a real-life frontiersman Hugh Glass in the early 19th-century. The western-thriller is based on true events of his survival odyssey as he narrowly escapes death after being mauled by a bear while on a fur trapping expedition.

Watch the trailer for "The Revenant" below:

https://youtu.be/FhcBf1Q5ueY