Knuffman's game-winner was set up by a 44-yard completion from Trenton Norvell to Lance Lenoir. Norvell was 18 of 35 for 333 yards and two touchdowns. Lenoir had four catches for 120 yards and Nikko Watson ran for a career-high 174 yards and two scores.
Southern Illinois got a 25-yard touchdown run by Cameron Walter and Kenny James' 70-yard interception return for a score to go up 33-28 early in the fourth. But Western Illinois forced a fumble and Brett Taylor scooped it and went 21 yards to put the Leathernecks up by a point with 9:35 left.
Daquan Isom returned the kickoff 52 yards to set up Austin Johnson's 32-yard field goal to put Southern Illinois up by two, but it only served to set up the dramatic conclusion.