LYNN — They say defense wins championships. Like most topics in sports, debatable. 

What wasn’t debatable, however, was that defense catapulted No. 5 St. Mary’s to a win in Thursday night’s MIAA Division 3 Round of 32. The Spartans nearly doubled up No. 28 Dedham, 62-33, at the Tony C. Gymnasium.

“We, basically, went man-to-man. The constant ball pressure was important,” said St. Mary’s head coach and Athletic Director Jeff Newhall. “We tried to push them away from the basket and force them into challenging shots.”

Mission accomplished. 

And no one personified the words ‘inspired defense’ more than Bella Owumi (12 points) of the Spartans, who shut down Dedham’s backcourt from start to finish.

“Their ball-handler (Megan McNamara) was a forward-type player, but she handled the ball pretty well,” Newhall said. “I think their offense, kind of, went stagnant when Bella started defending her because she’s just so quick, she’s long, and she plays right in your face.”

Better yet, St. Mary’s (18-6) was coming off its longest break of the season.

“I think we’ve been off for 10 days,” Newhall said. “But, the most important thing is that you’re able to come to practice tomorrow.”

Two big reasons for that: Charleigh Green (10 points) and Juliana Conte (9).

Eighth-grader Green made an immediate impact off the bench, finishing four layups in the first quarter – one that ended, 16-8, in favor of the defending champs.

“I was seeing open spots where I could just easily finish around the hoop,” Green said. “I was just playing my game… He (Newhall) says to just be myself.”

He said some more about the Beverly native.

“Just her energy and her presence,” Newhall said. “This is her first year here and that was her first playoff game.”

Green said she “plays for the crowd.”

“I love the crowd,” she said. “When it has amazing energy, I just love it.”

And if her offense got things started, Conte’s downtown shooting continued the barrage. St. Mary’s led by 19 points (30-11) at halftime and 37 (52-15) after three.

“Juliana hit some big threes in the second quarter to open things up a little bit, then we hit a few more in the third quarter, which opened up the inside,” Newhall said. “The first few minutes of the second half – if there was any chance of a situation transpiring, I think we put that to rest in the first two to three minutes of the second half.”

Dedham showed some life with its off-ball movement, but the Marauders struggled with their passing and finishing.

As for St. Mary’s, highlight plays of the second half included Sophia Lafontant’s triple to beat the third-quarter buzzer, and Lina Owumi’s slick drop-off pass to Chloe Bergeron for a layup. 

Reese Matela went home with nine points – and strong inside defense – to round out the Spartans, who advanced to the Sweet 16 (TBD).

“The expectations are always the same,” Newhall said. “We’re able to play at home again, so I think that’s significant… We’re going to have to beat a good team.”