Published: Aug 06, 2012 8:28 PM EDT
Updated: Aug 07, 2012 6:31 AM EDT

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 said Ball will be worked back into practice slowly, and he hopes Ball 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.

"I think in the end, if there was proof or anything that comes out that he was involved, it absolutely, positively would," Bielema said Monday, after the Badgers' first day of practice. "But I'm fairly confident that the young man that I've known over the last seven years of my life is a guy that's been pretty straightforward."

Ball was a Heisman Trophy finalist last season as a junior, scoring 39 touchdowns to tie Barry Sanders' NCAA record.

Police said Ball was walking down a street last Wednesday around 2:15 a.m. after "socializing" with friends. Two friends walking ahead of him turned around and saw Ball on the ground. The men had surrounded him and were kicking him in the head and chest.

Detectives investigating an assault subsequently identified "several persons of interest" and believe the altercation might be related to a fight a few days earlier. Investigators determined that a fight occurred late on July 27 and into the morning of July 28 involving Wisconsin students, members of the football team and others, according to a police statement.

Ball was present, but there is no indication he participated in the fight, police said.

"I do think that Montee feels very strongly that he wasn't involved in any way, shape or form, and he's never given me an indication to think otherwise," Bielema said.

Beyond that, Bielema was guarded in his comments.

"The accusation of the fight before that is really a police matter that I'm letting them handle," Bielema said.

Bielema said wide receiver Isaiah Williams and linebacker Cody Byers have been removed from the team's roster but didn't give a specific reason.

"Both are in Madison," Bielema said. "Both have an opportunity to join us here in the next couple of days. It's just dependent on what happens for us."

Asked whether those moves had any connection with the fight, Bielema said he wasn't able to comment.

"I guess people are going to have to assume what they want," Bielema said. "For me, as a head coach, when you're dealing with a situation like that, I have to make a decision on what I know, what I believe is real."

The area where Ball was attacked is on the edge of the Wisconsin campus and features multiple bars. Police have been dealing with what they say are combative crowds in the area all summer.

Bielema said he thought the incident has taught Ball "how much potential hate can be driven toward him in a short amount of time by so many people."

Bielema reminded players that getting into trouble would have consequences.

"In my seven years as a head coach, we have not had many situations pop up," Bielema said. "I don't expect to go through my entire coaching career without some of these things popping up. I know that I recruit kids of high quality and high character. If there's a situation where a couple guys are involved in it, I told every one of them, 'Hey, if you did something to ring the bell, you're going to have to pay the price.'

"I'll let the police work this out, give us the direction we need to go in and move forward."