ORONO — It was one of the most damning phrases an athlete can ever apply to his team: “mentally lazy.”

That’s how Maine senior Connor Leen saw it Saturday, and who can argue after the Black Bears lost 5-1 to Notre Dame before an announced crowd of 4,350 at Alfond Arena?

Maine surrendered three goals in a disastrous 84-second stretch late in the second period and couldn’t keep pace with the Fighting Irish (12-14-4, 7-5-4 Hockey East).

“I wouldn’t say they were any faster than us. Maybe we didn’t keep up with them because we were mentally lazy,” said Leen, who scored Maine’s lone goal in the first period. “We have good speed on this team and we’re not really afraid of anyone.”

Notre Dame scored 4:18 into the game when Anders Bjork sent a rebound shot past Maine goaltender Matt Morris.

Leen answered at 7:23 with his sixth goal of the season, this one coming when he brought the puck behind the net, wheeled around just before he reached the corner and seemed to surprise Notre Dame netminder Cal Petersen with a sharp-angle shot that whistled into the goal.

The score was tied 1-1 until 1:49 remained in the second period, when Sam Herr tipped in an Austin Wuthrich slap shot. Vince Hinostroza followed with a goal 39 seconds later, and Jake Evans concluded the flurry when his shot deflected off of a Maine defenseman’s skate and through Morris’ pads.

The Black Bears (10-17-3, 5-9-2) never recovered. Petersen, a freshman, made 33 saves to preserve the lead.

“When you’re letting up goals back-to-back-to-back, it can be really demotivating,” Leen said.

“The goals weren’t really highlight-reel goals, they were pretty sloppy, just hard-working goals, second chances, where Mo would make good first saves and they got second whacks at it.”

Hinostroza added an empty-net goal with 1:19 left to cap a six-point weekend for the sophomore, a Chicago Blackhawks prospect. He had three assists Friday and bedeviled Maine with his superior skating.

“Today, we put together three periods and every line was going. When we get all four lines going full speed, protecting the puck, controlling the puck, we’re a really good team,” Hinostroza said.

Morris felt he needed to make more plays, especially in the pivotal sequence.

“That three-minute stretch is unacceptable. I need to make at least two of those saves, if not all of them,” he said.

For Maine Coach Red Gendron, the result was particularly frustrating because he had warned his team in the morning to avoid the kind of letdown that cost the Black Bears in a December series against New Hampshire. In that one, Maine followed a 5-2 win with a tepid performance and a 7-4 loss. Gendron showed them video clips of what went wrong then, and then watched in disbelief as a sequel unfolded. Maine was coming off a strong performance in a 4-4 tie with Notre Dame on Friday.

“We had to be laser-lock focused and intense for the game tonight. Clearly, that didn’t happen,” Gendron said. “How many times did we miss passes that were bouncing off our sticks? We just weren’t sharp. Why? I don’t know.”