Sorensen was 35 of 46 passing, and Fesi Sitake added 107 receiving yards and a TD for the Thunderbirds (2-4, 1-0 Great West), who snapped a three-game losing streak.
Jake Landry threw two touchdown passes and Joel Schwenzfeier returned an interception 100 yards for a score for the Fighting Sioux (2-4, 0-2), who led 14-0 after the first quarter.
Major Gray found the end zone on a 1-yard run early in the second as Southern Utah scored the game's next 31 points. Sorensen followed with TD passes of 7 and 12 yards.
After a field goal by Brock Miller, Austin Minefee capped the Thunderbirds' scoring with a 12-yard run in the fourth.