Less than two weeks ago, the St. Mary’s and Arlington Catholic hockey teams didn’t even know if they were going to be allowed to participate in the state tournament following an ugly post-game brawl back in January.The two teams were banned from post-season play barring appeal following the fight, but the MIAA’s Ice Hockey Committee granted both teams appeals and allowed them to enter the Division 1 North tournament.Since then, the two Catholic Central League/Large teams have seemed to be on a collision course. And tonight (7:40) at the Chelmsford Forum, the two will meet for the third time this season with nothing less than a Division 1 North title up for grabs.”We’ve had a great schedule that’s prepared us for this tournament,” St. Mary’s coach Mark Lee said. “We’re just glad that we had a chance to play and that we’re going to play a very tough Arlington Catholic team.”The Spartans’ (16-8-1) road to the final has seen them play all three of their tourney games in Chelmsford. They opened with a 2-1 win over No. 13 seed St. John’s (Shrewsbury), but looked to be heading for an early exit in the quarterfinals against Waltham last Saturday.The No. 5 seed had a 2-1 lead with under a minute to go when Mike Restuccia’s prayer was answered to force overtime and eventually a shootout where Donald Hesse stopped all five shots he faced to help the Spartans escape, 3-2.”Hesse has been great for us in this tournament and all year long,” Lee said. “And it’s a great time for him to be playing his best hockey.”St. Mary’s semifinal game proved to be shockingly easy against top-seeded Burlington. The Spartans scored goals on their first three shots of the game and never looked back in a 5-1 win over the Red Devils.Even more amazing about St. Mary’s sudden run to the finals is that they are doing it with a team that has only three seniors that skate a regular shift.”I am so proud of this young team,” Lee said. “They are reaping the benefits of their hard work and are playing very well.”St. Mary’s task, however, won’t be easy tonight as they face a team they know very well.The Cougars also had to brush off a scare in their opening round game against Reading, playing through three periods and an overtime of scoreless hockey before winning in a shootout.AC followed with a 5-1 dismantling of No. 3 Woburn in the quarterfinals before jumping out to an early 2-0 lead on Central Catholic in the semis en route to a 3-1 win over the Raiders.The teams split during the regular season, with each taking a game on the other’s home ice. Round three will be for a trip to TD Garden and the big stage.