Sylvester Stallone and Arnold Schwarzenegger are good friends who have shared the screen in films such as “The Expendables” and “Escape Plan,” but that wasn’t always the case for the action icons.

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The two were box office rivals throughout the 1980s and 1990s, which Stallone recently admitted to Forbes was the reason behind the two hating each other for a long time.

“We really disliked each other immensely,” Stallone said. “We were… this may sound a little vain, but I think we were pioneering a kind of genre at that time and it hasn’t been seen since really.

So the competition, because it’s his nature, he is very competitive and so am I… and I just thought it actually helped, but off-screen we were still competitive and that was not a healthy thing at all, but we’ve become really good friends.”

Stallone dominated the action genre in the 1980s with the Rambo movies, plus films like “Cobra” and “Tango & Cash.” Schwarzenegger kick started the 1980s with two of his most iconic action roles in “Conan the Barbarian” (1982) and “The Terminator” (1984), the latter of which surely made his competition with Stallone go into overdrive. Schwarzenegger’s action success continued with “Commando” (1985) and “Predator” (1987).

Speaking on a recent episode of “The Jonathan Ross Show” (via Insider), Stallone said of the pair’s rivalry, “We couldn’t stand to be in the same galaxy together for a while. We truly, truly loathed each other.”

These days, Stallone and Schwarzenegger are good friends and collaborators. Schwarzenegger popped up in a cameo appearance in Stallone’s 2010 franchise-starter “The Expendables” and then reprised the character in two sequels.

Schwarzenegger originally was not going to return for “The Expendables 2” when it appeared the franchise might be taken away from Stallone.

“There is no ‘Expendables’ without Sly,” Schwarzenegger said at the time. “I would never do the movie without him, no.”

Schwarzenegger left the franchise after the third movie because he thought his role was underwritten. He told Vanity Fair, “You know, I think the first and second one were terrific… But, the third one, I thought my part was not written well… I didn’t believe that I had any value in the movie.

I love the franchise, by the way. I think it’s a spectacular franchise.

I think that Sly has good ideas, what he wants to do with it, and I think if they write a really good script [in] which my part is very well-developed, I would do it. If not, then I won’t do it.”

Stallone and Schwarzenegger graced the big screen again in 2013’s “Escape Plan,” which grossed $137 million worldwide. The film led to two sequels, both of which starred Stallone.