Moviemaker Renny Harlin helped Sylvester Stallone combat his fear of heights on the set of 1993 mountain climbing action movie Cliffhanger by playing on the actor's ego.

Stallone left the Finnish filmmaker feeling a little nervous when he confessed to his phobia on his first day in the Italian Alps after checking out the set's 11,000-foot (3,352 metre) base camp.

Harlin tells Entertainment Tonight, "I said, 'That's where our set is,' and he's like, 'So who's going to go up there?' I said, 'You are.' He looks at me and he says, 'You gotta be kidding. I have a fear of heights. The highest I will ever go is the heels of my cowboy boots!'

"It became my task to trick him into wanting to be higher in the mountains... I knew his psychology and I put him in a situation where it would have been embarrassing for him to, in front of the crew, refuse to get there. Obviously, I was able to get him there, and then once I got him to relax he was more than willing to do everything, and even more than I wanted him to do.

"The highest peak that we worked was 13,000 feet high, and there he was right on the edge, basically doing whatever it took."