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Carl Weathers, the outstanding athlete and actor, died at the age of 76 on Friday. People around the world have been mourning his death, and Sylvester Stallons issued a touching tribute to his Rocky co-star on social media.

Weathers played Apollo Creed in the first four Rocky films, and he formed a close friendship with Stallone throughout the years. After Weathers' death, an emotional Stallone stood in front of a painting of Creed and Rocky Balboa and spoke about what Weathers meant to him.

"When he walked into that room and I saw him for the first time, I saw greatness, but I didn't realize how great," Stallone said. "I never could have accomplished what we did with Rocky without him. He was absolutely brilliant. His voice, his size, his power, his athletic ability, but more importantly his heart and his soul."

Stallone, getting choked up, ended with a heartfelt message for his sparring partner.

"Apollo, keep punching."

Weathers and Stallone worked together on the first Rocky film, which was released in 1976. The duo was immensely popular, and the two worked side-by-side through Rocky IV, which came out nearly a decade after the first movie in 1985.

Stallone wasn't the only major action star that Weathers worked with in his prolific acting career. He co-starred alongside Arnold Schwarzenegger in Predator, and he worked with Charles Bronson in Death Hunt. Weathers also got top billing in action movies of his own, such as Action Jackson and Hurricane Smith.