MONTREAL -- There wasn't anything to be done about the play that gifted the Canadiens the eventual game-winning goal over the Islanders.

Well, perhaps if the Isles had mustered more than 18 shots on goal and just Kyle Okposo's second-period score, the outcome could have been different. But a tie game in a tight, competitive third period turned completely on the skate of linesman Michel Cormier, leading to a 4-1 defeat for the Islanders.

"You can say it's just bad luck, but it's incredibly frustrating at the same time," Okposo said. "We hadn't given them anything to that point and then that happens."

Nathan Beaulieu tried to lead Tomas Fleischmann with a pass up the boards, but Johnny Boychuk tipped it. The puck was out of Fleischmann's reach and would have gone deep into the Islanders' zone.

Instead, it hit Cormier's skate, sat perfectly for Fleischmann to enter the Isles' zone and he fed David Desharnais for a one-timer that Jaroslav Halak had no chance to stop, giving the Canadiens a 2-1 lead.

Brock Nelson had a semi-breakaway half a minute later, but he didn't even get a shot off on Canadiens backup goaltender Mike Condon, who only had to make 17 saves. The puck went the other way and the Isles got to chasing in their own end, forgetting about Brendan Gallagher, who made a waist-high deflection of Max Pacioretty's shot at 7:55. An empty-net goal made the final result seem far more lopsided than it was.

"They're a great team and we were working hard to limit their chances," Boychuk said. "You see the puck go behind you, you tip it so he can't get the puck and then it's sitting right there for him and it's the game-winning goal."

The Islanders allowed only 24 shots to the NHL's top team and only Dale Weise's power-play goal over the first 46 minutes.

John Tavares didn't completely look like his old self after missing three games due to illness, missing an open net on a second-period power play, but he had five of the Isles' 18 shots and worked hard in the tight areas near Condon.

"We just didn't generate enough, especially in the third," Tavares said.

The one-goal night left the Islanders with only eight goals in their last five games and a 1-2-2 record over that span. They have tightened up defensively since some wide-open performances over the first 10 games and Thursday night was no different.

"I think we made our main focus to improve defensively the last few games and we've done a pretty good job of that," Okposo said. "We're squeezing our sticks a little tight at the other end though. We need to get some more rushes from our 'D,' we as forwards have to try and take games over a little more."

Even with some of those failures on offense, this one stung. Jack Capuano said Cormier came over to apologize to the bench, but there isn't anything to be done about that kind of play.

"It happened to us against Buffalo, too," Capuano said of a play in the 2-1 loss to the Sabres on Sunday that was similar -- a clearing attempt by the Isles hit the linesman and allowed Buffalo to come back the other way during an Islanders' line change. This one was more directly impactful, though.

"We played a great team really well and it's too bad it had to come down to that," Capuano said. "It's unbelievable."