The Chargers struck first on a Nick Novak 28-yard field goal, but Robbie Gould's 42-yard field goal and Marion Barber's 1-yard touchdown run gave the Bears a 10-3 lead. Philip Rivers would then find Antonio Gates on an 8-yard pass, but Jay Cutler and Kellen Davis would connect to give the Bears the lead in the second quarter. In the third quarter, Rivers would find Vincent Jackson to tie the game, but Cutler would then score two more touchdowns on a one-yard run, and Charles Tillman would force a Ryan Mathews fumble. Cutler would then throw a 24-yard touchdown pass to Johnny Knox to make the score 31-17. Novak would then score on a 48-yard field goal to end the game with a Bears 31-20 victory. Cutler passed for two touchdowns and ran for a third. He also completed 18 of 31 attempts for 286 yards and a 97.0 passer rating. However, Cutler would break his thumb when he was attempting to tackle Antoine Cason early in the fourth quarter, who had intercepted his pass. The injury would end his season.
Question: How many incomplete passes did Cutler throw?
Answer: 13