In early November, Stallone recalled the moment Lundgren "pulverized" him on the set of "Rocky IV" during an intense boxing scene between their characters Rocky Balboa and Ivan Drago.
"I didn't feel it in the moment but, later that night, my heart started to swell, my blood pressure went up to 260 and I was going to be talking to angels," Stallone recalled in a YouTube video. "Next thing I know I'm on this emergency, low-altitude flight. I'm in intensive care surrounded by nuns."
Lundgren’s thunderous punch to Stallone’s chest proved to be a near-fatal experience for Stallone, who is now one of the Swedish actor's closest friends in Hollywood.
In a new interview with Fox News Digital, Lundgren admitted it was a "pretty serious" situation.
"I was 10 years younger and in very good shape those days and we ended up hitting each other quite hard. When we wrapped in Vancouver where we shot the last fight he ended up in the hospital. I think he was off for about two weeks," Lundgren recalled.
Despite the gravity of Stallone's emergency, Lundgren insisted action film actors are prone to taking hits here and there.
"You know, we all end up incurring all these injuries being an action star. I suppose that was one of the more interesting ones he's been a part of," Lundgren said with a chuckle. "I'm glad he made it. Good for me."
Stallone and Lundgren have gone on to film several other films together, including the action thriller franchise "The Expendables," which has a fourth installment coming in 2022. The towering fitness enthusiast said his near-knockout of Stallone is still something the two joke about today.
"Ah, we laugh about it. We both got hit in the face in that picture," Lundgren said of the 1985 film. "In those days there were no effects so if you wanted a head shot when the sweat flies out of your hair and blood comes out of your mouth you had to shoot it. You had to do it. So we both had to take those shots but we joke about it sometimes."
Stallone has previously confessed that when Lundgren was first cast as Drago, he "hated him immediately."
"I had to find a superhuman being as an opponent, someone who would be overwhelming," Stallone said at the Cannes Film Festival in 2019, adding that he found Lundgren to be a "perfect" Soviet rival for Balboa. "This is what I would imagine they would create as an athlete — someone who is literally perfect. Indestructible. Shoulders, calves, forearms, giant butt, neck, back, everything."
Lundgren, a martial arts specialist, told us the feeling was mutual. He said he was taken aback by Stallone's prowess during filming.
"I was very impressed with him too because I was 10 years younger and I was a karate champion. I was used to fighting for real, and he kept up, and I remember at the time I was impressed that he was in that good of shape."
Stallone released "The Ultimate Director's Cut" of "Rocky IV" back on Nov. 12 which features never-before-seen footage of the cult classic.