Jett's basket with 35 seconds remaining broke a 61-61 tie, and Ellis made four free throws to keep the Billikens (5-3) in control and give them back-to-back victories for the first time this season.
Saint Louis has won both of its games since the death of coach Rick Majerus, who stepped down before this season and was replaced by Jim Crews. Majerus died Saturday in Los Angeles.
It was the teams' first meeting since 1981.
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.
|Texas San Antonio||3-15||13||5-27|