Jay Allen's Tigers kept the game close in the first quarter trailing 16-10 at the break.
Both teams used full-court pressure in the second quarter. Niangua got the better end of the period and extended their lead to 10 going into halftime with a 32-22 edge.
With three minutes left in the third quarter, Kong Lee penetrated the lane and laid in a "dipsy-doo" off-balanced runner and was fouled. He made his free throw to complete the 3-point play.
James Kho followed with a steal and lay-up, which brought the Tigers within 5 points.
That was as close as it would get, as Niangua went on to a 61-43 victory, improving its record to 4-5.
"We struggled defensively tonight, allowed too many points in transition, didn't close out on their shooters and got beat on the boards," said coach Allen. "We are going to have to get better at giving consistent effort for all four quarters if we are going to win games."
Scoring for Exeter: Lee, 19 points; Colten Stringer, 10; Michael Brattin, 5; Blake Walker, 3; and; Kho, Ty Pendergraft and Terry Cook, 2 points each.
Exeter will face Halfway at noon on Dec. 27, at the Walnut Grove Tournament.