Zac Efron has promised that the Baywatch movie will be "big, real and raw".

The actor will star alongside Dwayne 'The Rock' Johnson in the forthcoming big screen version of the NBC soap opera.

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He told BBC Newsbeat: "These days you kind of have to be R-Rated if you want to make it for our audience."

He added that he'll be preparing for his latest role by "hitting the gym with The Rock".

"He's going to be bench-pressing me and lifting me up," the 27-year-old joked.

Johnson welcomed the actor to the cast on Twitter, while Efron replied: "So stoked brother - baby oil for 2 plz."

Efron will play a young lifeguard who teams up with a veteran (Johnson) to save their beach from an environmental disaster.

Identity Thief and Horrible Bosses director Seth Gordon formally signed on for the Baywatch movie last month.