Fourth-ranked Ohio State is unbeaten but faces another big challenge without standout Bryant

There were worries about quarterback Braxton Miller's health, about suspensions, about other injuries, then about beating a good Wisconsin team.

Now that those concerns have dissipated in the wake of a 31-24 victory last week, No. 4 Ohio State's coaching staff gets hit with yet another major question:

How do you replace perhaps the leader of your defense?

Coach Urban Meyer and the rest of the Buckeyes are confronting that as they prepare for their second major challenge in as many weeks, a primetime matchup at No. 16 Northwestern on Saturday night.

Christian Bryant, a starter in 27 games in his four-year career and the Buckeyes' third-leading tackler this season, was lost for the rest of the year with a broken ankle late in Saturday's game.