The two players shot a combined 16 for 23 (69.5 percent) from the field. Gfeller shot 6 for 11 from beyond the 3-point arc.
Montana (7-6, 2-0 Big Sky) shot out of the gate when Breunig made three of the Grizzlies' first four shots and led 9-3. But Southern Utah fought back and took a 22-20 lead on a pair of Casey Oliverson free throws with 8:37 to play before halftime.
Gfeller made back-to-back 3s and Michael Oguine's layup with 5:51 before the break gave Montana the lead for good. The Grizzlies led 40-28 at half.
Montana extended the lead to 52-35 on two baskets and four free throws by Breunig, and layups by Walter Wright and Oguine.