Williams made four 3-pointers and nine of Harris' points came from the stripe and the Titans (4-7) shot 54.4 percent from the field.
Aaric Murray had 21 points and grabbed 12 rebounds for Texas Southern (3-7). Forty-five rebounds, 22 on the offensive end, helped Texas Southern stay close -- despite shooting 39 percent.
After not making a 3-pointer in the first half, Cal State Fullerton made three in a span of 2:17 and took a 65-56 lead. Texas Southern scored the next eight to make it a one-point game. But Williams' 3-pointers started a 9-0 CS Fullerton run for its first double-digit lead of the game at 74-64 with 4:51 left.
Cal State Fullerton made 7 of 8 free throws in the final minute to secure the victory.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.