Trubisky will start the season as Chicago's No. 2 quarterback, Larry Mayer of the team's official site reports.
Trubisky leapfrogged Mark Sanchez for the top backup job after completing 36 of 53 passes for 364 yards with three touchdowns and no interceptions during the preseason. Instead of watching Sunday's opener against the Falcons strictly from a student's perspective, he'll have to be ready to take the field if Mike Glennon gets injured or benched. Sanchez likely will be inactive for the Week 1 contest.