GORHAM — With this new sense of parity in Class A boys’ hockey, a matchup between two of the better teams figured to be a close one.

And so it was, when South Portland/Freeport/Waynflete played Scarborough at the University of Southern Maine Ice Arena.

Close, that is, “until we ran into penalties,” South Portland Coach Joe Robinson said.

Scarborough broke open a tight game in the third period, with an early power-play goal, and two more on a five-minute major, as the Red Storm topped South Portland 6-2 on Monday.

Nolan Matthews had a hat trick to lead Scarborough. Jacob Brown added two power-play goals. Zach Chaisson scored the other. Goalie Peter O’Brien made 18 saves.

Scarborough, playing only its fourth game – after starting the season with exhibition games in New Hampshire – improved to 3-1, with its one loss coming to unbeaten Lewiston.

South Portland’s unbeaten streak ended at four as the Red Riots dropped to 3-2-1 (their other loss coming to defending state champion St. Dominic).

Both teams are in the top six in the new 13-team Class A rankings (with no regions) – behind Lewiston, Falmouth, St. Dom’s and Thornton Academy.

“The way this league is set up, there’s going to be a lot of tight games,” Scarborough Coach Jake Brown said. “It’s just going to be who is going to continue to get better and who’s going to stay healthy for the playoffs.”

Those playoffs don’t start for two months. Lewiston may be the favorite in Class A, but both Scarborough and South Portland have hopes of a favorable seed.

On Monday, South Portland showed its might early, controlling most of the first period, but having little to show for it.

“In the first period, we were all over them,” Robinson said. “But we were 0 for 6 on odd-man rushes. One was a breakaway, and one was a 2-on-0 and we don’t get a shot off. If we capitalize on two or three of those six chances, it’s whole different game.”

Instead, South Portland scored first (Dylan Hannan at 10:19), but lost the lead before the first period ended.

Matthews scored from a scrum in front of the crease, at 12:14. The energized Red Storm kept pressuring.

Defenseman Ethan Jasa brought the puck deep and centered it – which Matthews one-timed in at 14:10.

“Great pass,” Matthews said.

Jasa could see the momentum turning.

“They came out fast but we’re a team that battles,” Jasa said. “We came out with three lines and, in the second and third periods, we were relentless.”

Still, South Portland tied it on Eric Walker’s power play goal at 6:24 of the second period. Then the relentless attack began. Matthews broke the tie for good at 10:28, coming out from behind the net and firing, for a 3-2 lead.

“I didn’t think we took care of the puck enough (in the first period),” Brown said. “Once we established the puck in their end, off the forecheck, that’s our game. We work hard down low.”

South Portland came out quickly in the third period, but a tripping penalty gave Scarborough its third power play. A puck came hard off the glass, and Jacob Brown was there to wrist it in at 1:55, for a 4-2 lead.

The Red Riots’ hoped for a comeback were stifled by a five-minute major penalty for boarding. Two goals later, it was 6-2.

“Not our day, that’s for sure,” Robinson said. “It’s kind of early … It’s pretty cool that it’s just Class A now (with no regions). The competition is right across the board. The playoffs will be interesting.”

Scarborough plays Portland/Deering on Thursday and Class B power Greely on Saturday. South Portland does not play again until Jan. 9 versus Cape Elizabeth.