Tune, a redshirt senior in his first season as a starter, was injured during the final drive of the 32-31 loss and underwent surgery that night. Sophomore Derek Thompson replaces Tune and will start Saturday's game at Army.
Riley Dodge, a redshirt sophomore who started at quarterback last season, will be Thompson's backup. Dodge, the son of head coach Todd Dodge, moved to receiver in the spring due to elbow problems. He'll return to working full-time as a quarterback this week.
Tune narrowly beat out Thompson in a summer competition for the starting job. Todd Dodge cited Tune's experience as the reason he chose the senior over the sophomore. Thompson is 5-of-7 passing for 40 yards this season.
Tune was 39-for-66 for 525 yards and four touchdowns in two games, both UNT losses.
Six other players who were on the Mean Green's two-deep roster have been ruled out for the season: CB Chris Neal (ankle), CB Steven Ford (ankle), C J.J. Johnson (foot), WR Benny Jones (ankle), RB/TE Micah Mosley (foot) and RB/TE Greg Brown (knee).