"I tore my ACL & MCL. I'm done for the season" Manigault tweeted.
Gators head coach Chuck Reedy confirmed the news to Live 5 Sports on Thursday saying Manigault was injured in a non contact drill during Wednesday's practice.
Junior Dominique Jefferson, who spent last season as the primary backup to Dantez Bennamon, is expected to take over the starting duties at quarterback.
Manigault accounted for over 1700 yards of total offense for West Ashley in 2013 including close to 1100 yards rushing. He also had 17 total touchdowns.