The No. 17 Yale men’s hockey team fended off No. 3 Boston University’s nation-leading offense for a full 48 minutes on Friday in the NCAA Tournament Regional Semifinal game. But it was what happened in the next 20 minutes of play that ended up determining the game — and the Elis’s season.

The Bulldogs (18–10–5, 12–6–4 ECAC) fell to the Terriers, 3–2, in overtime to end their season at the very beginning of the NCAA Tournament. Yale held a 1–0 lead after two periods — largely thanks to a dominant second period and strong play from its star goaltender, Alex Lyon ’17 — but BU’s offense came alive in the final minutes, tallying a pair of goals in the third and then clinching the win with a goal by forward Danny O’Regan, 7:27 into the overtime period.

BU (27–7–5, 14–5–3 Hockey East) then defeated No. 7 Minnesota-Duluth by the same score on Saturday and will head to the Frozen Four in Boston on April 9. Yale, meanwhile, was the last team to secure a spot in the tournament and the first to exit the 16-team field.

“It’s no mystery why [Yale] is in this tournament,” BU head coach David Quinn said after the game. “They play as hard as anyone we’ve played against. They’ve got a great goalie. It really was everything we thought it’d be.”

Goals for the Bulldogs came from defenseman Nate Repensky ’18 and left wing Frankie DiChiara ’17, who also helped out with a screen and was credited with an assist on Repensky’s goal.

Mainly due to dominance near the end of the game, BU outshot Yale 42–23, with 20 of those 42 shots coming in the third and overtime periods. Lyon stopped 39, tying his season high for saves — a stat that came in Yale’s eerily similar 3–2 overtime loss to Harvard just two weeks before.

After a scoreless first period in which Yale managed just six shots and posed few challenges for BU goaltender Matt O’Connor, the Bulldogs’ strongest play came during the second period of the game, when they generated numerous chances on the power play and outshot the Terriers 13–11.

Yale had a strong showing on its first power play of the period and continued outshooting BU in the middle of the frame, but it was not until a second power play opportunity that the Elis took the initial lead.

Just 18 seconds after Terrier forward Ahti Oksanen was called for elbowing, Repensky received a pass from forward Mike Doherty ’17 and fired it towards the net from the point. DiChiara was cutting across the ice in front of O’Connor’s eyes, allowing the laser shot to get past the goaltender and into the net.

Terrier forward Evan Rodrigues said his team played noticeably looser after the initial Yale lead, as BU had no reason to hold back. Yale head coach Keith Allain ’80 added that he was hoping for more goals early on for this reason.

“[The game was] not exactly where I wanted to be. I would have been 4–0 after two,” Allain said. “I think it was the kind of game we thought it would be. We felt that it would be to our advantage if they were chasing us rather than us chasing them, but it was not exactly where we wanted to be.”

In the third period, it was the Terriers’ turn to warm up offensively, as they held multiple long possessions with quick passing to start the period. Lyon saved BU’s first seven shots, including one acrobatic kick save, but with 12 minutes remaining in regulation, BU finally produced a series of passes that Lyon was not able to keep up with.

Oksanen, who had committed the penalty leading to Yale’s goal, ultimately got possession of a failed clear by the Elis and finished with an open net in front of him to level the score at one.

Just three minutes later, BU took a lead for the first time as Rodrigues slid a shot from the side through Lyon’s five-hole.

Yale continued playing scrappy offense throughout the rest of the period, failing to keep the puck consistently in BU’s zone and gaining chances primarily through odd-man rushes.

With seven minutes remaining in the game, however, Yale was able to string together enough passes to score as forward Carson Cooper ’16 passed to forward Cody Learned ’16, who found DiChiara in the middle of the zone for a snipe just over O’Connor’s left shoulder.

Neither team threatened significantly afterwards until near the end of the period, when Yale successfully killed off a penalty with three minutes remaining in regulation. BU remained on the offensive in the final minute after the penalty and hit the post with less than five seconds on the clock, but Yale narrowly escaped to send the game into overtime.

A hooking penalty on defenseman Rob O’Gara ’16 in those final seconds, however, forced the Elis to kill a penalty for the first two minutes of the overtime period. Yale succeeded in that task — its fifth successful penalty kill in as many chances — which forward Trent Ruffolo ’15 said should have helped create a scoring opportunity later in the period.

“We looked to gain momentum off of that kill,” Ruffolo said. “Our goal going into overtime was to take care of that kill first, and then we could get back to our game.”

But the Elis were able to put only two shots on O’Connor before a BU goal decided the game. Forward Jack Eichel, a favorite for the 2015 Hobey Baker award, fired a shot off Lyon’s leg pad, and O’Regan was able to recover the rebound and put it into the net.

The overtime loss, Yale’s first ever in an NCAA Tournament, came as a disappointment to Eli fans who felt that the stage was set for an upset title run similar to that of 2013. But Allain said he left the ice happy with the efforts of his team.

“I’ve been proud of this group all year long,” Allain said. “I’m not thinking about pride right now, because this is what I expect from this group … this is what they are and this is what they do, so they’re just being themselves.”

Elsewhere in ECAC Hockey, Harvard fell 4–1 to Omaha on Saturday, while North Dakota bested Quinnipiac, also by a score of 4–1. BU, North Dakota, Providence and Omaha will play in the Frozen Four in two weeks.

This article has been updated to reflect the version published in print on March 30, 2015.