ESPN’s FPI favors Auburn in eight games this season. This not does mean that a successful season is dependent on whether or not Auburn wins those eight games plus an upset over another team on the schedule.
An upset is not specifically defined by what the AP poll or ESPN says about a matchup. Part of what makes up a matchup, or a breakdown of a game, includes the eye test. Ole Miss was a top 15 team coming into Auburn last year. The Rebels lost 31-20. On paper, it was an upset. Lower ranked team beats higher ranked team.
Why did the Rebels lose? A big part of what held Ole Miss back were their injuries. Despite being ranked highly, they were not playing complete football. It was to the point where it was almost just a win, not an upset. Even Vegas favored Auburn by a field goal.
Auburn needs to win against a team that the eye test and oddsmakers believe the Tigers should not beat.
They also need to not choke against an opponent they are better than. Games against Missouri, Ole Miss, Mississippi State and Arkansas come to mind.