Southern Illinois (3-3) shot 57 percent as a team and made 18 of 20 free throws. Sean O'Brien had 13 points, Jordan Caroline added 12 points on a perfect shooting day - 4 of 4 from the floor and the line - and Bola Olaniyan had 10 points.
NAIA-member Olivet Nazarene was led by Aaron Larson with 14 points. Tyler Crater added 10 points.
The game was tied at nine when SIU scored eight unanswered points - including a 3 by Tyler Smithpeters - and the Salukis led 40-28 at the break after shooting 58 percent from the floor and 10 of 12 from the line.
Olivet Nazarene cut its deficit to eight early in the second half, but SIU proved too strong down the stretch.