By Christian Holub
January 05, 2016 at 01:04 PM EST

Creed has won wide acclaim for reinvigorating the Rocky franchise, thanks in large part to the magnetism and drive of new star Michael B. Jordan. But as Rocky creator and Creed costar Sylvester Stallone told Jimmy Fallon on Monday, it takes more than just a killer workout to become part of the Rocky family: until you take a punch from a real world-class boxer, you’re just a “Dead Man Walking,” according to Stallone. 

As part of the initiation rite, Jordan agreed to let Tony Bellew (a real-life British boxer who plays Jordan’s opponent “Pretty” Ricky Conlan in the film) punch him for real, knocking Jordan to the floor in footage previously shared by Stallone


“When a real pro hits you, it isn’t like you see in these bar-room brawls or Westerns with a big punch,” Stallone said. “It’s just ‘boom,’ and next thing you know you are talking to angels.” 

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As the star of six previous Rocky franchise films, Stallone has taken his share of punches from world-class athletes, but the strongest punch, he said, came from Rocky IV costar Dolph Lundgren.

“Dolph Lundgren put me in the hospital for four and a half days,” Stallone said. “It was unbelievable. He hit me so hard in the chest that the next thing I knew I was on a low-altitude flight to intensive care at St. John’s Hospital surrounded by four nuns.”