Groton — The end of Thames River’s season to remember began slowly going wrong when it had a punt blocked in its end zone for a safety five minutes into Tuesday night’s CIAC Class MM quarterfinal.

Gradually, ponderously North Haven continued the Crusaders’ demise just like its single wing offense that eats away at a defense in small bites.

The Nighthawks’ defense attacked much faster, however, and shut out one of the state’s highest scoring offenses in a 50-0 rout at Grasso Tech.

The fourth-seeded Crusaders finished the season 10-1. It was their first playoff appearance.

“My boys are getting tired playing both ways,” Thames head coach Craig Sylvester said, “but they fought hard. I mean, (North Haven) just pound-and-pound it (with the run) and that’s a good team.

“To me, that’s the best team in (the) division and I think they’re going to win it all.”

Thames was the state’s second-highest scoring team during the regular season (485) and allowed just 19 points. Its seven shutouts tied it for 13th all-time for most in a season, according to the Connecticut High School Football Record Book.

Fifth-seeded North Haven (9-2) ran 42 times for 362 yards and seven touchdowns.

The Crusaders had five first downs and 130 yards, 51 of which came on one Justin Outlow run.

“They surprised me in the first quarter with how physical they were playing because you don’t see that on the film,” Nighthawks head coach Tony Sagnella said about Thames. “When you’re looking at some of the games that they’re in, you could see a difference between our conference (the Southern Connecticut Conference Tier 1) and theirs (the Connecticut Technical Conference). So, you know, you have to get on the field and see what happens.

“I give their coaches a hell of a lot of credit and their kids a lot of credit because they were holding their ground with us (early). They weren’t shying away. They weren’t backing down.”

Jeffrey Karavas ran a team-high 15 times for 74 yards and a touchdown for North Haven. He also intercepted a pass at his team’s goal line in the third quarter when Thames had its best chance to score.

The Nighthawks will host No. 8 Wilton in Sunday’s semifinals at 12:30 p.m. Wilton knocked off top-seeded Sport and Medical Sciences Academy co-op, 13-6

Thames had a punt blocked in its end zone on its first drive for a safety.

North Haven got the short field on the free kick. Karavas ran for a 2-yard touchdown to give his team a 9-0 lead with 4:22 left in the quarter.

The Crusaders were able to get two first downs on their next drive and advanced to the Nighthawks 44.

Jack Philistin was sacked for a 6-yard loss by Brendan Ryan on third-and-9, however, and Thames was forced to punt.

Adam Pandolfi ran for a 37-yard touchdown on fourth-and-4 as the Nighthawks went ahead, 16-0, to start the second quarter.

North Haven started its final drive at its own 35 with 4:41 remaining in the first half and drove 65 yards on 13 plays, 12 of which were runs. The other was a spiked pass to stop the clock.

Camren Thompson scored on a 1-yard run as the Nighthawks pushed their lead to 23-0 with 22 seconds left in the half.

“We did the best we could and it wasn’t good enough,” Sylvester said. “But guess what — we’ll refocus and be ready for next year. And I’m proud of these seniors. ... (They) helped build this program.”

n.griffen@theday.com