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.
Forward Kennedy Meeks, who has averaged 9.4 points and 6.5 rebounds at North Carolina, has pulled out of the NBA draft and will return to the Tar Heels.
Cal big man Ivan Rabb could have been selected in the top 10 of the NBA draft. Instead, he's returning to Berkeley to make himself, and the Golden Bears, stronger.
Devin Williams' decision last month to sign with an agent and enter the NBA draft has left West Virginia in a tough spot.