Montee Ball -- Cops Investigating Possible Fight BEFORE Campus Attack

Montee Ball -- and several of his University of Wisconsin football teammates -- may have been involved in a fight several days before the 2011 Heisman Trophy finalist was attacked on campus yesterday ... TMZ has learned.

Law enforcement sources tell TMZ ... cops have received tips about a brawl at a UW football player's home roughly one week before Ball was jumped on campus.

According to our sources, cops have been told Ball was at the home ... and along with some of his teammates, may have participated in beating up a non-football player.

Cops were never called to the scene and no police report was ever filed.

But sources tell us ... investigators are now looking into the possibility that Wednesday's attack on Ball was in retaliation for last week's incident.

We've contacted the University of Wisconsin's athletic department -- so far, no comment.