MISSOULA, Mont. (Interstat) — The Montana Grizzlies, stymied for a half by a resilient Cal Poly team, erupted for 21 points in the fourth quarter to turn a defensive struggle into a decisive 28-9 victory on Saturday at a sold-out Washington-Grizzly Stadium.

The fifth-ranked Grizzlies remained perfect on the season, improving to 5-0, while the Mustangs fell to an even 3-3.

For the first 30 minutes, the game was a story of missed opportunities for Montana and opportunistic play by Cal Poly. The Mustangs’ defense, led by an interception from safety Mason Rivera, repeatedly bent but did not break, holding the potent Grizzlies offense off the scoreboard entirely in the first half.

Cal Poly quarterback Ty Dieffenbach capitalized on one of the few sustained drives of the half, connecting with Brooks Wheatley on a 26-yard touchdown pass early in the second quarter. The Mustangs added to their lead as time expired in the half, with Noah Serna booting a 27-yard field goal to send the visitors into the locker room with a surprising 9-0 advantage.

The momentum shifted decisively in the third quarter. On Cal Poly’s second possession of the half, Dieffenbach’s pass was intercepted by Montana cornerback Kenzel Lawler, who returned it 21 yards for a touchdown. The pick-six ignited the crowd of 26,000 and cut the deficit to 9-7, providing the spark the Grizzlies’ offense desperately needed.

Montana’s offense, which had sputtered for much of the game, finally found its rhythm in the final period. Quarterback Keali’i Ah Yat, who finished 27 of 41 for 257 yards, engineered a methodical drive that was capped by a 24-yard touchdown pass to the versatile Michael Wortham, giving Montana its first lead of the day at 14-9.

The Grizzlies then put the game away on the ground. Running back Eli Gillman, who had a stellar day with 123 rushing yards, broke loose for a 17-yard touchdown run to extend the lead. He added a second rushing touchdown, from 13 yards out, with just under two minutes remaining to seal the victory. Gillman’s two fourth-quarter scores were part of a dominant final frame for Montana, which outgained Cal Poly significantly after halftime.

The Montana defense was relentless, intercepting Cal Poly quarterbacks four times. In addition to Lawler’s game-changing return, Caleb Otlewski, Geno Leonard and Prince Ford each recorded an interception, snuffing out any hope of a Mustang comeback.

Dieffenbach completed 15 of 33 passes for 225 yards, one touchdown and three interceptions for Cal Poly. Paul Holyfield Jr. led the Mustangs’ ground game with 53 yards on eight carries.

The Grizzlies’ win sets up a matchup with Sacred Heart at home next Saturday. Cal Poly returns home for a bye week before hosting Montana State on Oct. 25.

According to Interstat’s game simulator, the final score was lower than the projected Montana 42, Cal Poly 29 outcome. The same service’s ELO system had given the Grizzlies a 97.30 percent probability to win, a forecast that ultimately proved correct after a sluggish start.