SALEM – It’s been a decade since the St. Mary’s High boys basketball team last made it to the Division 4 North final, but the Spartans are heading back thanks to a 75-64 win over Manchester-Essex Tuesday in the semifinals at Salem High School.Click here for a photo gallery.St. Mary’s will play Winthrop Saturday at the Tsongas Arena.Given the fact the Spartans and the Hornets played each other twice during the regular season and that each won in the other’s gym and neither game was particularly close, this one was up for grabs.But the one thing about familiarity is that there’s no secret what has to be done to win. In this case, the key was keeping Manchester-Essex’s 6-6 senior guard Joe Mussachia from doing too much damage.”He’s probably one of the best players in Division 4, maybe in the state,” Spartans coach Kevin Moran said. “We had to make a concerted effort to keep him under control.”In the two regular-season meetings, Mussachia averaged about 18 free throws per game and he was in that ballpark again last night, scoring 13 of his team-high 23 points from the stripe.Although the game was tied three times in the first quarter, Alex Fiste’s hoop with 47 seconds left before the half put the Spartans on top for good. Still, St. Mary’s was never able to relax. The Spartans got the lead up to 10 in the second quarter, but the Hornets pulled to within four when Chris Bishop buried a three with five seconds remaining.”I never felt comfortable,” Moran said. “At least not until there were only 14 seconds left.”The Spartans spread the offense around, with Nick Gagliolo and Devin Thompson each scoring 21 points and Ronsanto Campbell netting 14. Sophomore Randolph Thurman had six and Luis Rijo, five.”This team (St. Mary’s) has kind of been coming on for a while,” Moran said. “They worked hard throughout the summer. I stressed to them that this is a chance of a lifetime.”St. Mary’s, the No. 6 seed, reached the finals with wins over St. Clement and Maimonides and now Manchester-Essex, the No. 2 seed. The next hurdle will be beating Dave Brown of Lynn’s Winthrop team. Brown is a graduate of St. Mary’s. Winthrop reached the final with a 71-58 win over Georgetown Tuesday night.