Ratkovich's touchdown was the fifth lead change of the fourth quarter, capping a five-play, 59-yard drive that took 45 seconds. Eric Carrera sealed the victory for the Leathernecks (1-8, 1-4 Missouri Valley) intercepting Austin Simmons' pass near the goal line with 4 seconds left.
The Coyotes (3-6, 2-3) took a 34-31 lead on Caleb Vander Esch's 3-yard TD reception with 1:24 left in the game.
Connor Sampson completed 31 of 50 passes for 368 yards, three touchdowns and no interceptions for Western Illinois. Ratkovich had 116 yards from scrimmage and two total TDs, and Tony Tate caught six passes for 100 yards and a score.
Simmons passed for 274 yards, three touchdowns and an interception for South Dakota. Kai Henry rushed for a career-high 145 yards.
The Leathernecks' last win came against Southern Illinois on Nov. 3, 2018.
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