Scott hit two jump shots and a free throw early in the second overtime to give unbeaten Colorado (6-0) some breathing room against the game Tigers (1-6) and Dinwiddie sank two free throws with 9 seconds remaining in the period to ice the victory.
Scott and Andre Roberson both grabbed a dozen rebounds for the Buffaloes, who shot 39 percent from the floor and a prodigious 33-of-44 from the free throw line.
Omar Strong hit nine 3-pointers and finished with 39 points for Texas Southern. Fred Sturdivant notched 12 points and 11 rebounds.
Texas Southern led 39-29 at halftime but was outscored 30-20 in the second half. Sturdivant's layup with 43 seconds left in regulation tied the score 59-59 and sent the game into overtime.