When Chris Hemsworth signed on as part of the star-studded voice cast for “Transformers One,” he thought he’d just be sitting in a chair, reading lines.

Watch Hemsworth talk about voicing Orion Pax in the “Chris on the Physicality” featurette:

“The action sequences in this film are insane,” says the actor in a new featurette. “It actually takes a lot more physicality than I first assumed. I thought I’d just be sitting in a chair, reading lines. But I was jumping around and having to throw punches and make noise. There’s a lot of excitement and a lot of fun.”

In Transformers One, the first-ever fully CG-animated Transformers movie, Hemsworth voices Orion Pax/Optimus Prime. Transformers One is the untold origin story of Optimus Prime and Megatron, better known as sworn enemies, but once were friends bonded like brothers who changed the fate of Cybertron forever. Hemsworth is joined by Brian Tyree Henry (D-16/Megatron), Scarlett Johansson (Elita-1), Keegan-Michael Key (B-127), Steve Buscemi (Starscream), Laurence Fishburne (Alpha Trion) and Jon Hamm (Sentinel Prime).

“Feels fantastic to be officially part of the Transformers franchise,” says Hemsworth in another featurette. “What intrigued me was the origin story. Two best friends that become enemies, and then the birth of a hero.”

Find out more about what drew Hemsworth to Transformers One in the “Chris on the Franchise” featurette:

Transformers One, distributed in the Philippines by Paramount Pictures through Columbia Pictures, opens in Philippine cinemas September 18. Join the conversation with the hashtag #TransformersOne and tag @paramountpicsph