Ruben Guillandeaux put in a layup with 19 seconds left to lift La Salle over Saint Louis 78-77 on Wednesday night.
Down 75-68 with about four minutes to go, Earl Pettis and Guillandeaux hit back-to-back 3-pointers for the Explorers (12-13, 4-6 Atlantic 10) to make it a one-point game.
Brian Conklin answered with a pair of free throws with 2:04 left put the Billikens (8-15, 3-7) ahead 77-74.
But La Salle's Tyreek Duren responded with two free throws of his own and Guillandeaux soon made the winning layup.
Guillandeaux finished with 20 points. Jerrell Williams added 20 points and 11 rebounds for the Explorers while Aaric Murray scored 18 points.
Conklin led Saint Louis with 18 points while Kyle Cassity scored 14 and three players - Dwayne Evans, Mike McCall and Jordair Jett - each scored 10.
