Sylvester Stallone Shares Footage of 'Creed' Co-Star Michael B. Jordan Getting Knocked Out on Set

— -- Michael B. Jordan completely transformed his body to portray Adonis Creed, the boxer son of heavyweight boxing champion Apollo Creed and friend of Rocky Balboa in the fourth installment of the "Rocky" franchise, "Creed."

With the movie now swinging in the box office, Jordan's co-star and onscreen mentor Sylvester Stallone shared behind-the-scenes footage of the young actor taking a real punch.

Stallone, who reprised his role as Rocky in the film, said Jordan was "getting KO'd for real! But he got up and did it again! That's called guts!!"

Jordan has been outspoken about his physical transformation for "Creed," revealing that he gained over 20 pounds of muscle for the role.

He told ABC News last month that he underwent an "extreme diet change." Jordan said he "stripped down my diet completely. Grilled chicken, brown rice, broccoli and a lot of water. I worked out two to two three times a day, six days a week. And ... if you do that consistently for about 10 months your body will change."