Lamar (0-3) took a 6-0 lead in the second quarter on a pair of 26-yard field goals by Chris Esqueda and turned the ball over deep in South Dakota territory twice.
Theis capped a 13-play, 75-yard drive by scoring on a 2-yard run with 2:14 left in the half to send the Coyotes (2-1) into intermission with a 7-6 advantage. Theis added a 32-yard scoring run in the fourth quarter and Thomas scored on two short runs in the second half. The pair combined for 35 carries. Aidan Bouman completed 7 of 9 passes for 96 yards and a touchdown to JJ Galbreath, but was picked off once.
Robert Coleman was 13 of 23 for 119 yards for Lamar and threw one of the Cardinals' two interceptions.
AP college football: https://apnews.com/hub/college-football and https://apnews.com/hub/ap-top-25-college-football-poll