The Champ (1979)

Genre: Drama | Sport
Tagline: The most poignant love-triangle of all - a father, his son, and the woman who came between them.
Runtime: 121 min
Language: English

Plot:
Billy Flynn, an ex box champion, is now horse trainer in Hialeah. He makes just enough money to raise his little boy T.J. over which he got custody after his wife Annie left him seven years ago. T.J. worships The Champ who is now working on his come-back in order to give his boy a better future. But suddenly Annie shows up again ...

http://www.imdb.com/title/tt0078950/
http://en.wikipedia.org/wiki/The_Champ_(1979_film)