The action stars have a lighthearted brawl in their film The Escape Plan, with Sly later telling Metro UK in an exclusive interview that Arnie would win a real-life fight.

He joked: ‘Arnold would debate me into killing myself. He would talk me into doing it. Like in Silence of the Lambs.’

During an interview this week, the 67-year-old action hero revealed the magnitude of their feud to US talk show host David Letterman.

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He stated, “We had a violent hatred. Have you ever had that ever? Competition where you really had an arch enemy that kind of brings out the best in you. As Arnold would say, it really pushed you to accelerate.”

The rivalry between the two was so intense that Stallone declared that he despised “the fact that [Schwarzenegger] was on the planet, basically.”

“After a while, I started to like this competition, this one-upmanship,” the Rocky star stated, adding that he exploited the challenge to push himself.

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“He’d get a bigger gun. I’d shoot more people. He’d shoot more people. But then, he went into science fiction, which kind of left me behind.”

With a starring part in the acclaimed 1976 picture Rocky, which he also co-wrote, Stallone broke through to the big time. The Rocky franchise lasted far into the 1980s, but Schwarzenegger’s star rose to the point that he threatened to eclipse Stallone’s with a succession of blockbuster action pictures like Predator, Commando, and The Running Man.

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The couple has now put their tumultuous relationship behind them. They appeared among a supporting cast of action hero royalty in The Expendables in 2010, a series that has now spawned two sequels.

The film Escape Plan will be released in UK theaters tomorrow.