The Expendables 3 star Sylvester Stallone was in rare form at a recent An Evening with Sylvester Stallone, telling a packed Phones 4U Arena in Manchester, England, some stories about his career in the movies. One of the more interesting anecdotes was about his hate-hate relationship with Dolph Lundgren during the shooting of Rocky IV.

After watching the legendary war between middleweight boxers Marvin Hagler and Tommy Hearns, Stallone decided to ask co-star Lundgren, who played Rocky’s nemesis Ivan Drago, to really try and knock him out in one of their fight scenes. Well, he got what he asked for.

“Hey I got an idea, for the first 45 seconds, really try to knock me out, I mean go for it,” Stallone explains. “Bad idea. He comes across—boom, boom! He catches me in the chest. Woah. Cut, cut cut, I am directing so I can do that. CUT CUT. He says, ‘What?’ I said, ‘What? I thought I had a car accident!

“Later that night my blood pressure goes up to 260, I go to hospital, they put me in an emergency jet and fly me back to America. Next thing I know I’m in intensive care for five days with nuns walking around.” Stallone went on to say that the insurance company would not pay out until after they saw the footage of the incident. Once they did, they wrote the check. “He hit my heart so hard that it banged against my ribs and started to swell, and that usually happens in car accidents. So I was hit by a truck!”

Check out the segment below where Stallone also talks about why he hated Lundgren from the get-go (they’re friends now), and he and Arnold Schwarzenegger‘s bitter ’80s rivals. Our executive editor even went so far as tricking him into taking the lead in Stop! Or My Mom Will Shoot, which was a box office bomb. Check out this review of An Evening with Sylvester Stallone.

And just to get you pumped ahead of your workout, here is a blast from the past with the Rocky IV training montage featuring Stallone as Rocky and Lundgren as Ivan Drago: