The Wildcats (8-2) could never shake the Tigers (1-10), who trailed by just six points with 1:13 remaining. But four free throws in the final 35 seconds protected Kansas State's lead.
A 7-0 run by the Wildcats -- five of the points were by McGruder -- gave them a 46-36 lead with 15:03 remaining. It was the first double-digit advantage of the game.
The lead grew to 53-38 with 12 minutes to play. But Texas Southern went on a 10-2 spurt that included 3-pointers by Penn and Gibbs.
With 7:40 left, Texas Southern trailed 55-48 and hung in until the final minute.