Over the course of a grueling 37-game season, DeMatha took its share of bumps and bruises, eager to prepare itself for the rigors of postseason hockey.

Through two rounds of the Mid-Atlantic Prep Hockey League playoffs, the Stags are showing they saved their best for last.

In Wednesday’s semifinal matchup with Gonzaga, the Stags scored two goals in six seconds — capped by Grant Grieco’s breakaway game-winner — to beat the Purple Eagles and advance to the MAPHL final with a 4-3 victory. DeMatha will face Landon — a 4-2 winner against St. Albans — in Friday’s final.

Gonzaga led 3-2 with just over three minutes left in the game when forward Vance Walter dislocated his kneecap in a center-ice collision with a DeMatha player, causing a 10-minute delay as trainers tended to the injured senior.

After the stoppage, DeMatha pulled goalie Stephan Fernandez and went on the offensive. Pat Tanski’s tap-in goal with 1 minute 36 seconds left tied the score and Spencer Keogh intercepted a pass off the ensuing face-off and Grieco beat Nick Platais for the decisive tally. But the Stags (14-20-6) had to survive a Gonzaga power play for the final 20 seconds to advance.

Landon celebrates an 8-2 victory over DeMatha in the 2011 MAPHL final. The two teams will meet again on Friday for this year’s championship game. (Doug Kapustin/FOR THE WASHINGTON POST)

“It was a back and forth game — almost like a tennis match,” DeMatha Coach Tony MacAuley said. “They sort of had us hemmed in the last 20 seconds, but we were able to fight it off and hang on.”

It was Grieco whose third-period goal forced overtime against third-seeded Spalding on Tuesday night and then — in the ninth round of a shootout — sent the Stags through to the semifinals with the game-winner. On Wednesday, the junior forward came through in the clutch once more.

“We were fortunate with a bounce or two against Spalding, and we got one or two tonight as well,” MacAuley said.

The score was tied at 1 after the opening period and at 2 following the second, setting up a riveting third period between the longtime rivals. The teams split their two regular season meetings with DeMatha winning 6-5 in December and the Purple Eagles taking a 2-0 victory earlier this month.

Fernandez faced 29 shots — 11 more than Platais — but helped his team hang in the game with timely stops.

Michael Logan, Ned D’Arcy and Chris Meloni scored for the Purple Eagles while Garrett Hasken and Steven Partlow also tallied for DeMatha. Keogh finished with a pair of assists.

In the other semifinal, second-seeded Landon scored three times in the third period to take out upset-minded St. Albans, 4-2, and earn a chance to defend its MAPHL title. Senior Max Greenwald scored twice on the power play, and Ian Schneider and Matt Potolicchio also scored for the Bears (16-2).

If their Jan. 6 meeting was any indicator, Friday’s final could be another close contest. Potolicchio’s hat trick gave Landon a 3-0 lead in that game, but the Bears had to fend off a furious DeMatha rally to escape with a 3-2 win.

“The parity in the league this year has made every team in it stronger this year, that’s for sure,” said MacAuley, whose Stags lost 8-2 to Landon in the 2011 final. “We know what we’re getting with Landon. We just want to come in and work hard and make the most of our chances. We hope it’s a good game - we hope it’s close.”