The Billikens (6-6) trailed for most of the first half and went into the intermission down 38-30. They opened the second half with an 18-3 run and never trailed again.
The Camels (5-6) used an 8-1 run to close within 60-56 on Chris Clemons' free throws with 3:34 left, but Goodwin stopped the momentum with a 3-point play and Saint Louis made 9 of 12 free throws to go with Davell Roby's layup to hold on to the lead.
Johnson made all three of his 3-point attempts, all six of his free throws and 4 of 6 overall from the field for Saint Louis. Hasahn French added 11 points and 12 rebounds.
Chris Clemons had 28 points and Marcus Burk had 20, accounting for all but 18 of the Camels' points.
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Isaiah Roby averaged 11.8 points and 6.9 rebounds per game as a junior at Nebraska.
NBA draft profile: Bruno Fernando
Bruno Fernando averaged 13.6 points and 10.6 rebounds per game as a sophomore at Maryland.
NBA draft profile: Matisse Thybulle
Matisse Thybulle averaged 9.1 points and 3.1 rebounds per game as a senior at Washington.