The Tigers (20-7, 10-2 Conference USA) relied on a barrage of 3-pointers to build an early lead, then used the long-range shooting to keep the Mustangs at bay as they made a second-half run.
After trailing 58-35 with 13:49 left, SMU cut the lead to eight, 66-58, with 3:11 left. Witherspoon, Sallie and D.J. Stephens each made a pair of free throws and Sallie hit a 3-pointer to push the lead back to 17 points, 75-58, with 1:05 to play.
Willie Kemp had 10 points for Memphis, while Witherspoon added eight rebounds and six assists.