Southern Utah built a 20-6 lead almost nine minutes in before the Bengals outscored them 23-13 and trailed 33-29 at halftime.
Austin Smellie's 3-pointer for Idaho State with 12:34 left ended a nearly four-minute scoring drought for both teams and the Bengals trailed 39-35. But Southern Utah regrouped and outscored Idaho State 21-11 over the next 6-1/2 minutes and led by double digits the rest of the way.
Dwayne Morgan scored 13, also off the bench, as the Thunderbirds' reserves outscored Idaho State's 36-16. Despite being outrebounded 34-29, Southern Utah (9-5, 2-1 Big Sky) committed just six turnovers and shot 26 of 53 (49.1%).