While the original film could have ended at that, the possibility of a sequel is pretty hard to deny. The rematch between Rocky Balboa and Apollo Creed? Classic.
The film takes place shortly after the original match. Rocky took his defeat humbly and returns to a normal life.
And then focuses on his new married life and the birth of his son.
But Apollo Creed gets letters claiming that his victory was rigged. He invites Rocky for a re-match, and the rest is history.
I'd say the fight was a bit better the original, and I love that "on the edge of your seat" ending to it.