Mercer scored 21 unanswered points after halftime.
Tee Mitchell's 42-yard receiving touchdown from John Russ put the Bears up 21-7 with 6:26 remaining. Mitchell finished with 101 yards on the ground and a rushing touchdown. Russ passed for 176 yards to nine different receivers.
Mercer and Austin Peay met for the first time last season, with the Bears jumping out to a 28-0 first-quarter lead en route to a 49-21 victory. Gerron had 196 yards in a losing effort.
The game was delayed 45 minutes prior to the opening kickoff because of lightning.