Movie about a boxer named "Rocky" (not Rocky Balboa)

When I was 8 years old, in 1983, I saw a movie about a boxer named Rocky, on HBO I think. The only thing I specifically remember about it is, after Rocky wins a fight, during the celebration, someone pours champagne over his head. That stands out in my mind because I thought it would suck to have anything poured over your head, and wondered why he didn't get mad.

His name being "Rocky" stands out in my mind because not long after that, HBO started showing Rocky III, which quickly became my favorite movie, but when I first saw it (which was also the first time I ever saw any Stallone Rocky movie) I wondered why "Rocky" looked so different compared to the other movie (at first I thought it was supposed to be the same "Rocky" character, and figured that maybe the other movie I'd seen was part I or II of the same series).