BOSTON — The last time Boston University beat Boston College in the Beanpot entering Monday night’s semifinal, the New England Patriots had three rings, the Red Sox had just won their second title since 1918 and the Celtics and Bruins still were trying to break decades-old championship dry spells.

In other words, it had been a while, as BU coach David Quinn pointed out Monday.

But one night after the Pats won their fifth Super Bowl and locked up Boston’s 10th title since the turn of the century, the Terriers finally ended their puzzling stretch of negative results in the Beanpot against their archrival with a 3-1 victory at TD Garden.

It was BU’s first Beanpot win over BC since the 2007 tournament when it topped the Eagles 2-1 in overtime in the title game. BC had won the previous six Beanpot meetings between the two foes.

And, just like it did in its previous two wins over the Eagles this season, Boston University did it with its defense.

Terriers goaltender Jake Oettinger made 22 saves, including 16 in the second period when the defense came down to Earth, and they killed all four Eagle power plays.

“If we’re going to go anywhere, it’s going to be with our goaltending and our D-core,” Quinn said. “… We do have the ability to get out of our own end, and if we continue to defend well, we’ve got a chance.”

Considering BU is one of four teams to allow two goals or fewer per game in college hockey this season, we’ll go out on a limb and say it has a very good chance.

Let’s check out a few more notes from an exciting night of college hockey.

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— Jakob Forsbacka Karlsson soon could make a living by scoring goals at TD Garden for the Boston Bruins. But on Monday, he did it for his current team. The Terriers center scored his 11th goal of the season in the first period and gave BU the early momentum.

— Perhaps the most puzzling stat from the second game was shots on goal. Boston College only had two in the first period and four in the final frame, but it outshot Boston University 16-3 in the second.

— Neither team was wildly successful on power plays, as BU was 1-for- 6 and BC was 0-for-4, but the Terriers did score a man down when Clayton Keller potted his fourth short-handed goal of the season, which is tied for most in college hockey.

— BU is 52-13 and BC is 35-30 all time in Beanpot semifinal games.

— Harvard is second in the nation in short-handed goals and they got another one Monday courtesy of senior Luke Esposito.

“First of all, some of our best players are penalty killers,” Esposito said. “Obviously you are seeing more and more of that at the highest level, and in college as well. I think that adds to it, and as a team we have a lot of speed, so whenever we get the chance to get up in the play and push them back, whether it’s just disrupting them, or trying to get a chance, we do that and I think we saw that tonight.”

Esposito’s short-handed goal in the third period proved to be the difference in Harvard’s 4-3 win over Northeastern.

–Harvard is heading to its first Beanpot final since 2008 and senior center Alexander Kerfoot thinks the biggest difference between the final and the consolation game will be in the number of people in the arena.

“I think it will be cool to come out for warmups and there will be more than seven people in the stands,” Kerfoot said. “I think for the last three years it’s been pretty demoralizing playing in the consolation game on that second Monday, no one wants to be a part of that. Obviously, this is a huge win for us but we want to go one step further and win the championship.”

Harvard head coach Ted Donato knows the Beanpot final will be an important moment for his fourth-ranked Crimson going forward.

“This senior class is some good hockey players, and great kids,” Donato said. ” But they really haven’t had the chance, and I don’t think until you play in that second game, I don’t think you really have a chance to experience the Beanpot until you play in the finals. So I think it’s an important step for our group. I’m happy for them and they aren’t satisfied.”

–The last time that Boston University and Harvard met in the Beanpot final was in 1998 which ended with the Terriers winning 2-1 in overtime.

— Harvard hasn’t beaten BU in the Beanpot since 1977, a 4-3 victory for the Crimson.

Thumbnail photo via Twitter/@Cam_McDonough