Simmons led a 13-play, 75-yard drive that ended with his 2-yard scoring pass to Caleb Vander Esch for a 7-3 lead with 5:29 left in the first quarter and South Dakota (4-6, 3-4 Missouri Valley Football Conference) never trailed again.
Kai Henry's 4-yard touchdown run with 9:14 to play made it a 17-6 score. The Leathernecks scored their lone TD when Joe Turk blocked Brady Schutt's punt that Daymon Murray recovered in the end zone.
Western Illinois (5-5, 4-3) quarterback Sean McGuire threw for 251 yards with 116 going to Clint Ratkovich. The Coyotes limited Western Illinois to 21 yards rushing on 22 attempts.
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