Many of the 6,286 in attendance at the Mullins Center left wondering what they had showed up for. That was because Boston University used its trademark defense to make a first-period lead stick in a 2-0 win over Massachusetts.

Netminder Sean Fields aided the defensive effort with a spectacular performance, making 25 saves for his fourth shutout of the season.

“It’s one of the better ones I’ve played all season,” Fields said. “It’s always nice to get a shutout. I was looking for a little redemption this time around.”

Brian Collins got the game winner at 4:37 of the first period on BU’s first power play of the game.

Brian Collins scored the only goal BU would need Friday (photo: James Schaffer).

Brian Collins scored the only goal BU would need Friday (photo: James Schaffer).

Freddy Meyer fed John Sabo down low for a point-blank shot. Gabe Winer made the save but Collins pounded home the weak-side rebound for a 1-0 lead at 4:37.

Winer was solid in net making 17 saves, but it was not enough against the experienced Fields.

“You get a shutout on the road and you’re happy,” Terrier head coach Jack Parker said. “I thought both goalies played well and Fieldsy was just a little bit sharper.”

BU was dominant in the first period but still managed only one goal.

The Terriers did not hold the shot advantage (7-7), but did hold UMass to mostly harmless shots from the perimeter.

“The forwards did a good job of letting me see the puck and keeping their shots to the outside,” Fields said.

“I think Sean did earn the shutout,” Mark Mullen said. “I guess we helped him out. We talked before the game about making sure we had enough guys on the backcheck.”

All while BU had the home squad on its heels.

Other than the goal, its best chance came when Ryan Whitney caught UMass in a line change and skated in alone on Winer.

Whitney tried a deke to the backhand but had the puck slide off his stick.

Mullen used a brilliant individual effort to turn a relatively level second period in the Terriers favor. He picked up the puck in the defensive zone and turned on the jets to beat the UMass defense down the right wing. Winer stacked the pads and went for the poke check but Mullen anticipated and lifted the puck into the shelf for a 2-0 lead.

“I kind of misjudged it,” Winer said. “I’ll take the blame for that one, it was a bad decision and a good shot.”

Otherwise the teams opened it up for an entertaining 20 minutes.

UMass had the majority left on a power play to start the first period, but Fields was up to the task. He stopped Marvin Degon on a screened shot from the point and then he stoned Thomas Pock on a good look from the faceoff circle.

“That’s one of the better power plays in Hockey East,” Parker said of UMass’s man-advantage. “I think we did a great job killing penalties.”

The Terriers had their own power play at the 3:35 mark and took full advantage. BU peppered Winer with shots from a myriad of angles but the freshman stood strong with four saves.

The Minutemen seemed to tilt the ice in their favor following Mullen’s goal. Their best chance came on a down low two-on-one when Pock found Tim Turner alone in the slot for a one-timer. But Fields read the play and moved to the top of the crease to deflect Turner’s shot to safety.

“If we bury the puck in those situations it’s a different game,” UMass coach Don Cahoon said. “We’ve got to finish.”

UMass carried the play in the third period but it was too little too late. The Minutemen had a five-on-three to work with in the third and ignited the crowd with what looked like a goal.

Turner fed a cross-crease pass to Chris Capraro, who had more than half the net to work with.

But the referee waved it off, the goal judge did not turn the switch and somehow the puck was kept out of the net.

UMass had another prime opportunity to cut the deficit with a power play at 11:23, but Fields, as he had the whole game, made big saves to keep the Minutemen at bay.

Turner had UMass’ best chance with a point-blank shot but Fields again gave him nothing.

With the win BU improves to 10-8-0 in Hockey East, 17-10-2 overall, while UMass drops to 8-12-0 (14-14-1 overall).

The announced crowd of 6,286 was the third-largest in UMass history.

“It’s something we hope we can continue to attract,” Cahoon said. “We want to win for them and we’ll work toward that end.”