MADISON, Wis. (AP) -- Wisconsin running back Montee Ball hasn't been cleared to practice as he recovers from a concussion sustained when he was roughed up by five men in an early morning incident near campus last week.

Badgers coach Bret Bielema says the team will work Ball back into practice slowly, and hopes he will be ready for the Sept. 1 season opener against Northern Iowa.

While police continue to investigate whether an earlier fight involving Badgers football players might have triggered the attack on Ball, Bielema doesn't believe the senior running back did anything that will jeopardize his standing on the team or his Heisman Trophy hopes.

Bielema said he believes Ball wasn't involved in the earlier fight. Bielema calls it a "police matter that I'm letting them handle."