Rocky II is the first film to show Rocky Balboa becoming heavyweight champion.
In the original Rocky, Rocky challenges Apollo Creed and goes the distance but loses the split decision. Rocky II continues the story with Apollo seeking a rematch and Rocky struggling with the physical and emotional consequences of the first fight.
The rematch ends when both fighters are knocked down in the 15th round. Rocky rises first, wins the bout and becomes the world heavyweight champion. The victory completes the competitive arc that began in the first film.
Rocky III then begins with Rocky already established as champion and defending his title against Clubber Lang. Rocky Balboa, released in 2006, concerns an older retired Rocky returning for an exhibition rather than his first championship victory.