WEST ROXBURY — The Catholic Memorial football team emphasized one word during the week of practices leading up to Friday night’s matchup with Brockton:

Finish.

The 10th-ranked Knights came through on their home turf, scoring three fourth-quarter touchdowns to secure a convincing 34-0 win over ninth-ranked Brockton.

“The past couple games and scrimmages we really haven’t finished, whether that be on our drives, going three and out on defense,’’ said senior quarterback Matt Marcan­tano.

“It’s a game of fundamentals, blocking, tackling, and securing the football,’’ said CM coach Dennis Golden. “And we just wanted to execute as well as we could and the kids came out and did it in the second half.

“Brockton played a great first half. They were taking the action to us, they established some run game, but our kids responded each time they got down in scoring territory. So we were able to battle, but credit to them for a great job.’’

Catholic Memorial (2-1) scored just once before halftime, when Harvard-bound senior Jack McGowan found the end zone on a 22-yard rush with 8:20 to play in the first quarter. Marcantano’s 2-point pass attempt fell incomplete.

Brockton (2-1) had a chance to answer late in the frame after senior Dion Amado recovered a CM fumble at the Knights’ 3, but two plays later Brockton had a fumble of its own and CM junior Dan Boyle came up with the ball.

Both offenses were stymied in the second quarter, and Catholic Memorial headed into halftime with a 6-0 lead.

“We were very fortunate [to be up] 6-0, it’s better than not,’’ Golden said. “Our D came up big when it had to.’’

The Knights gave themselves some breathing room halfway through the third quarter with a 2-yard touchdown run by senior Peter Scibilia. William Fay kicked the extra point to put the Knights ahead, 13-0.

Neither team could string together a successful drive for the remainder of the third, but the final 11 minutes belonged to CM.

First, Marcantano completed an 11-yard touchdown pass to senior Kyle Sonnie. The extra point gave the Knights a 20-0 lead with 9:53 to play.

“The line just started really doing a good job,’’ said Marcantano, who finished 16 for 27 for 148 yards with two TDs, and one interception.

“I think the play-action kind of worked for us, and the backside one-on-one was just wide open and a great receiver like Kyle will take that any day.’’

Less than two minutes later, senior lineman Matthew Rowan recovered a Brockton fumble, setting up first and goal for the Knights from the Brockton 8-yard line. Two plays later, Marcantano found McGowan open in the end zone with a 7-yard toss.

Brockton fumbled again on the first play of the ensuing drive, and once again, Rowan secured the loose ball.

Just over a minute after McGowan’s score, junior Nick Goffredo stepped in for Marcantano and completed a short pass to senior Emmett Forde, who spun out of two tackles and ran 27 yards to the end zone.

“It felt awesome,’’ Marcantano said. “This week at practice I feel like we’ve never really worked harder as a team. All summer we’ve just been preparing for this and it’s very rewarding.’’

Emily McCarthy can be reached at emily.mccarthy@globe.com.