Riley nailed a 3-point jumper with 1:22 left in the extra period to give Texas Southern a 69-68 lead. Janarius Middleton answered with a layup to put Jackson State out front 70-69 with 31 seconds remaining.
TSU's Madarious Gibbs missed a layup but Jason Carter came away with the rebound and was fouled. Carter left the game with an injured elbow. Chris Thomas was selected to shoot the free throws and he made both for the win.
Middleton led Jackson State (8-18, 6-7) with 18 points and 14 rebounds. Raeford Worsham and Kaven Barnard had 17 apiece.
Gibbs made two free throws with eight seconds left in regulation to send it to overtime.