WOULD you believe Dennis Hopper as Frank Sinatra?

The actor, who usually plays demented bad guys, will next portray the singer in the movie “The Night We Called It a Day.”

The trade paper Screen Daily reports Melanie Griffith will appear as one of Sinatra’s girlfriends and David Hemmings (“Blow-Up”) as his lawyer.

The flick, which begins shooting Oct. 21 in Sydney, is the story of a promoter who persuaded Sinatra to tour Australia in 1974.