MISSION VIEJO >> De La Salle was never supposed to stand a chance against Mater Dei-Santa Ana in Saturday’s CIF State Open Division championship game.

Especially after the SoCal powerhouse loaded with future college football stars went into the halftime locker room up by 23 points. De La Salle was destined to be yet another overmatched opponent.

Nobody told the Spartans.

“Like coach said, we said, ‘Can’t go out like this,’ ” senior running back Derrick Blanche said. “It clicked with us, that we had to put up a fight. And that’s exactly what we did.”

The Concord program fought back from the dead and gave Mater Dei everything it could handle — for one inspiring quarter, at least — in a gritty 37-15 loss at Saddleback College.

Down 23-0 to start the third quarter, quarterback Toa Faavae and running backs Blanche and Dominic Kelley propelled the Spartans downfield on a 65-yard, 11-play touchdown drive capped by Faavae’s 1-yard sneak.

After future Oregon defensive lineman Matt Johnson Jr. ended the next Mater Dei drive with a sack, the Spartans went back to work.

Faavae ran for a 41-yard touchdown right down the middle of the vaunted Monarchs defense, and Blanche rumbled in for the two-point conversion to help send De La Salle into the fourth quarter down just 23-15.

“Derrick opened up a great hole for me, and I just took it and trusted my speed,” Faavae said. “Everything was just clicking.”

DLS coach Justin Alumbaugh said that the team didn’t change the playbook or shift tactics. The Spartans simply started playing with more toughness.

“We were running the same plays we were running in the first half,” Alumbaugh said. “It was the same plays we ran against Pitt a few weeks ago.”

First-year Mater Dei coach Raul Lara said he was impressed by the Spartans, who famously defeated him in high-profile regular-season games at Long Beach Poly in 2001 and 2002.

“We knew we were going to be in a battle, and they gave us a battle,” Lara said.

The comeback was just not to be, though.

Oregon signee Jordan Davison finally provided the Mater Dei response in the fourth quarter to complete a 16-play, 92-yard drive, bowling over defenders on a tackle-breaking 15-yard touchdown with 8:19 left.

Mater Dei got the stop on the next drive and then scored another touchdown to secure the victory.

“They’re the No. 1 team in the country for a reason, and they were deserving of the win,” Alumbaugh said. “I wish we played a better first half and the margin for error is small for this kind of game. But I’m not disappointed, because it’s been an incredible year. I hate this feeling, and I’m livid because I’m a competitor … but that doesn’t mean this season is a wash.”

Mater Dei (13-0) started the night looking every bit like the team tabbed by many as the best team in the country.

Davison ran for a 2-yard touchdown on the first drive of the game, and Gavin Honore caught a 90-yard touchdown from Washington commit Dash Beierly to make it 14-0 in the first quarter.

The Monarchs outgained De La Salle 232 yards to negative-3 in the first period, and the second quarter wasn’t much better.

Aside from an impressive goal-line stand by the De La Salle defense in the second quarter, where the Spartans forced a turnover on downs, the fans who had traveled from Concord had little to cheer for early on.

“We weren’t playing our best football,” Faavae said. “Our defense was balling out and getting three and outs, and our offense left too many points on the field.”

Oregon commit Nasir Wyatt tipped a pass that fellow Mater Dei edge rusher Shaun Scott intercepted, and later in the quarter, the pair combined for a safety after De La Salle’s aforementioned fourth-down stop.

Kayden Dixon-Wyatt, a Bay Area native, made the East Bay powerhouse pay for leaving him open in the flat with a 21-yard touchdown reception on the ensuing drive right before halftime.

De La Salle lost its seventh consecutive state championship game, including five in the Open Division.

The Spartans had three weeks to prepare for the state final after defeating Pittsburg 10-7 in the North Coast Section Open Division title game on Nov. 22.

But just like the Serra program that reached the previous three state Open finals, De La Salle was unable to beat its Southern California opponent. The South has won eight consecutive Open Division state title games, with Mater Dei capturing five of them.

De La Salle has future major Division I players at a couple of positions. The Monarchs boasted seven of the top 100 prospects in California’s class of 2025, and every player on the Orange County team is expected to play high-level college football.

Since the Spartans’ four consecutive victories over Mater Dei, from 1988-2001, the modern-day Monarchs have won three in a row over De La Salle.

Mater Dei beat the Spartans in the 2017 and 2018 Open state championship games, 52-21 and 35-21.

This game was much more similar to the latter, and proved something to the Spartans, who haven’t won a state title since 2015 and ended this season 12-1.

“We knew we came into this as an underdog, and really made a statement hanging around with the best team in the country,” Blanche said. “That says a lot. I feel like we are a top team in the country, and we proved that tonight.”