The famed song for the theme from Rocky III, now in video format.
While not the first choice of song for this movie (Joe Esposito's "You're The Best"), it ended up being a huge hit for the fledgling band. And it was all because Sylvester Stallone liked their early stuff. That's quite the endorsement!
It's a reasonably standard straight-ahead rock-and-roll song, but it kick-started the band's career, as they went on to have a number of hits after this initial burst of great.