Aubrey Coleman had 30 points and nine rebounds for the Cougars (14-14, 6-8), and Adam Brown added 17 points.
Dia had 12 rebounds for his eighth double-double this season.
SMU, which trailed 39-33 at halftime, was on fire in the second half, shooting 66.7 percent (16 of 24) with nine 3-pointers. Houston helped by getting whistled for 15 fouls -- the Mustangs shot 23 free throws after intermission, making 20.