Sylvester Stallone opened up about a little-known story regarding his time filming "Rocky IV," revealing the experience nearly killed him.

The 75-year-old actor recently posted a video titled "The Making of Rocky vs. Drago by Sylvester Stallone" to his YouTube channel in which he said Dolph Lundgren, who played Rocky's Russian nemesis Ivan Drago, went off script and nearly beat him to death.

"I got really injured during the fight," he said of the movie's nail-biting boxing sequence. "I had to be flown into intensive care to California from Canada."

The "First Blood" star admitted that he encouraged Lundgren to go all out and show his "dominance" before filming.

"Well, he pulverized me," Stallone deadpanned, noting that Lundgren punched him right in the chest. Stallone said he didn't know how badly he was injured until after the cameras stopped rolling.

"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," the three-time Oscar nominee recalled. "Next thing I know I'm on this emergency, low-altitude flight. I'm in intensive care surrounded by nuns."

Stallone said his hospital stay lasted four days and, once he was discharged, he "had to go back and finish the fight."

He said he was upset by the movie's theatrical cut because the punch that sent him to the hospital was left on the cutting room floor, which is why he wanted to do a director's cut of the film.

"How could you take that out?!" Stallone quipped.

"Rocky IV" premiered in theaters in 1985 and earned $300 million worldwide during its box office run. The film's storyline continued in 2018's "Creed II."