More than three months removed from its season-opening loss to the same Terriers’ squad that used a 6-0 run in the final 20 minutes to hand UMass an 8-1 defeat Oct. 10, it appeared this time the Minutemen were going to flip the switch, taking the lead two separate instances in the last frame.

But what started as a competitive game Friday, in which UMass held a 5-4 advantage with 10 minutes, 32 seconds remaining, quickly turned into another third period attack by BU, who once again tallied six goals in the closing frame to secure a 9-5 victory at Agganis Arena in Boston.

Terriers’ defenseman Matt Grzelcyk’s first goal of the year with less than seven minutes remaining proved to be the game’s deciding score, giving BU a 6-5 lead. The power play goal came one minute after freshman Jack Eichel tied the game at five apiece, also on the man advantage.

In total, the Terriers capitalized on six power play goals (6-for-8), including five in the third period in which the Minutemen spent 12 of their 20 penalty minutes in the box.

“Our (penalty kill) let us down tonight,” senior captain Troy Power said. “We were not good enough on that. We definitely took a lot more penalties than we should have that led to being on the penalty kill in the first place.”

UMass coach John Micheletto said that one factor that helped the Minutemen (8-17-1, 3-12-1 Hockey East) stay competitive through the first two and a half periods was limiting their transgressions. Coming into Friday’s matchup with a conference-high 386 penalty minutes, the Minutemen only spent eight in the penalty box through two periods.

But once BU (16-4-4, 11-2-2 HEA) saw increased opportunities in the third period, Micheletto said that the Terriers showed the ability to capitalize, with the help of some unfortunate bounces.

“We had two blocks that wound up in the back of our net. That’s just bad puck luck,” Micheletto said. “We’re in the right spot, we’re doing the right thing and the puck deflects off of us because we’re willing to give up our bodies.”

Despite its defensive struggles against BU’s power play attack, UMass’ offense was also carried by the power play, which finished with three scores on the man-advantage.

Trailing 3-1 midway through the second period, Power initiated a Minutemen comeback with a power play goal following a slashing call on BU’s Danny O’Regan.

Forwards Shane Walsh and Frank Vatrano then each converted on third period goals while the Terriers’ Evan Rodrigues was in the penalty box for a five-minute major boarding call. The pair of goals gave UMass its first lead of the game at 4-3 five minutes into the final frame.

“We had some opportunities off the set that led to us being able to break them down into transition opportunities,” Micheletto said. “Our tenacity on the forecheck and in 5-on-5 areas certainly translated into a tenacity to get to the puck on the power play.”

The Minutemen’s last lead came at the 9:28 mark after freshman Riley McDougall netted his third score of the year, putting UMass ahead 5-4.

“I thought it was a pretty good college hockey game for 55 minutes,” Micheletto said. “It was back-and-forth and both teams were playing really hard and making plays in both directions.”

On a crowded score sheet, BU was led by a hat trick from Ahti Oksanen. Eichel added two goals and two assists while Grzelcyk contributed two assists along with his deciding goal.

For the Minutemen, Patrick Lee and Brandon Montour each recorded multi-point games with three and two assists respectively.

Looking ahead, UMass will next play Northeastern and No. 10 UMass-Lowell this Friday and Saturday.

Anthony Chiusano can be reached at [email protected] and followed on Twitter @a_chiusano24.