EXCLUSIVE CONTENT Get ESPN+ Michigan and six other undefeated teams facing prove-it games this weekAdam Rittenberg, ESPN Senior WriterSep 28, 2021, 07:00 AM ETClose College football reporter. Joined ESPN.com in 2008. Graduate of Northwestern University.Follow on XEmailThere are certain games on every team's schedule that provide clear markers of progress. For Michigan, this week's trip to Wisconsin was always going to be that game in 2021.