http://www.countingdown.com/movies/2756500

First search I saw, there is probably much more detail on other sites. That site gives a different synopsis which sounds a bit 'poor'. From what has been rumoured also, a different storyline is that Balboa trains Rocky Jnr for a title fight. I'd prefer the latter as I struggle to see Rocky beat a current HW champ. I know it's the movies, but they can't get away with that stuff no more.