The win by the Vandals (12-7, 4-2) snapped Montana's seven-game win streak, dealt the Grizzlies (11-7, 6-1) their first home loss and left Weber State alone atop the Big Sky at 5-0. It was Idaho's first victory in Missoula since 1999. The Vandals rejoined the Big Sky last season.
Brandon Gfeller's long 3-pointer got the Grizzlies within two, 60-58, with 22 seconds left but Sanders made two free throws and, after Gfeller missed another 3-point try, Ty Egbert added a final point.
Montana led 24-22 at halftime but Idaho outscored the Grizzlies 22-5 over the first 10 minutes of the second half.
Sanders was 13 of 14 from the line.
Breunig finished with 20 points and 10 rebounds. Gfeller scored 14 points, making four 3-pointers, but they came on 12 attempts.