FOXBOROUGH — What did it take to derail an unbeaten season for upstart Pope John XXIII in the Division 8 Super Bowl Saturday morning?

A once-beaten St. Bernard’s of Fitchburg squad that was equally impressive in its ability to put points on the board with speed and execution.

In the second-highest-scoring game in MIAA bowl history, the Bernardians held off Pope John, 46-35, on the strength of a 22-point fourth quarter at Gillette Stadium for the program’s first championship since 1997.

St. Bernard’s (12-1) racked up 330 yards, including 250 on the ground behind a 15-carry, 105-yard, two-touchdown effort from senior fullback Xavier Marty.

“Not for nothing, we are a pretty quick football team, too,’’ said St. Bernard’s coach Tom Bingham.

The Bernardians’ took a 16-14 lead into halftime, but both offenses put up a prodigious amount of points in the second half.

Junior quarterback Dom Cuevas set the tone for St. Bernard’s when he scrambled to his right, and while absorbing a hit threw a strike that found junior tailback Walter Morales (two rushing touchdowns, one receiving). Morales broke free into the middle of the field and into the end zone for a 39-yard touchdown.

“I was scrambling out and I saw the defensive end come up and I really couldn’t see anyone open and Walter made a great play to get open,’’ said Cuevas. “After the play, my head was hurting a little bit, but it went away.’’

Cuevas was instrumental to the victory, completing 5 of 6 passes for 80 yards and a touchdown, to go along with a rushing score and four 2-point conversions.

“He’s the glue on both sides of the ball, he keeps it going, he’s the quarterback of the defense and the offense,’’ said Bingham.

Marty, who battled a hamstring injury all season, played both ways for the first time since Week 1.

“I never really thought I’d get here, I’ve been battling injuries all year,’’ said Marty. “But I’m very proud, these kids gave it their all.’’

With St. Bernard’s ahead, 24-20, an explosive final frame kept Pope John in the game. After senior quarterback Anthony Mejia (7 of 13 for 106 yards, 3 touchdowns) went down with an ankle injury, sophomore back John Smith-Howell (19 carries, 116 yards) shifted behind center and took off for touchdown runs of 55 and 2 yards to cut the deficit to 3.

“[At] 38-35, we tried an onside kick,’’ said Pope John coach Paul Sobolewski, who guided the Tigers to a 12-1 finish in the first year of his second stint at his alma mater. “It is what it is. We have a freshman kicker, we have all sophomores out there. This is nerve-racking for them.’’

A 35-yard touchdown run by Morales and Marty’s 2-point rush with 2:03 left were the difference.

“It’s a tough ending to a great season, 12-0 coming in, we kind of overachieved a little bit with four or five seniors on our roster, but I think this is good for the development,’’ said Sobolewski.

In 2017, the program’s first after being dormant for four seasons, Pope John finished 2-6.

“It hurts losing in a Super Bowl, there’s no doubt about it. I think moving forward, it gives our kids something to strive for,’’ said Sobolewski. “It shows them what we have to get to win at this level.’’

PIVOTAL PLAY: With 2:03 remaining in a 38-35 game, St. Bernard’s junior tailback Walter Morales sprinted around left end on his way to a 35-yard scoring run, putting the game out of reach for the Bernardians.

St. Bernard’s 46, Pope John 35

at Gillette Stadium, Foxborough

St. Bernard’s (12-1) 8  8  8 22 — 46

Pope John (12-1) 6  8  6 15 — 35

 PJ — John Smith Howell 34 pass from Anthony Mejia (rush failed)

 SB — Xavier Marty 9 run (Domenic Cuevas run)

 SB — Domenic Cuevas 2 run (Jakai Alexandre pass from Domenic Cuevas)

 PJ — Roshad John 23 pass from Anthony Mejia (Anthony Mejia run)

 SB — Walter Morales 39 pass from Domenic Cuevas (Domenic Cuevas run)

 PJ — Jesus Rivera 23 pass from Anthony Mejia (pass failed)

 SB — Xavier Marty 6 run (Domenic Cuevas run)

 PJ — John Smith Howell 55 run (Greg Smith run)

 SB — Walter Morales 3 run (rush failed)

 PJ — John Smith Howell 2 run (Erik Flores kick)

 SB — Walter Morales 35 run (Xavier Marty run)

INDIVIDUAL STATISTICS

 RUSHING — PJ, John Smith Howell 19-116, Greg Smith 8-34, Anthony Mejia 4-27, John Rashad 3-22, Jesus Rivera 3-(-9); SB, Xavier Marty 15-105, Walter Morales 7-42, Maxwell Bigelow 6-38, Domenic Cuevas 8-9, Jakai Alexandre 1-3

 PASSING — PJ, Anthony Mejia 7-13—106; SB, Domenic Cuevas 5-6—80

 RECEIVING — PJ, Jesus Rivera 3-36, John Smith Howell 1-34, Roshad John 1-23, Jose Davalia 2-13; SB, Walter Morales 2-51, Maxwell Bigelow 2-22, Jakai Alexandre 1-7

Steve Sousa can be reached at steven.sousa@globe.com.