The Bruins had proven to be fairly adept at catch-up hockey in this Eastern Conference semifinal series against the Montreal Canadiens. But as it usually does, catch-up hockey caught up to the B’s in Game 3 last night.

The B’s gave their most mistake-filled performance of these playoffs and Tuukka Rask was unable to come up with the key saves his team needed in a 4-2 loss at the Bell Centre. With the win, the Canadiens will carry a 2-1 series lead into Game 4 tomorrow night.

After spotting Montreal a three-goal advantage by midway through the contest, the Bruins never fully recovered.

Patrice Bergeron scored late in the second period on a deflection of defenseman Torey Krug’s shot, and Jarome Iginla tipped defenseman Andrej Meszaros’ blast past Canadiens goalie Carey Price with 2:16 left in the third with Rask pulled to add some drama to the proceedings.

But when a faceoff win eluded Krug at the Montreal blue line, Lars Eller finally sealed it for the Canadiens on an empty-netter with three seconds left.

For the third time in this series and fourth time in the last five playoff games, the Bruins faced at least a two-goal deficit. Despite the late push, the more deserving team got the win.

“I said it after last game: It’s not going to happen every time,” Bergeron said of the comeback victories. “We’ve got to make sure we do a better job of playing and having a good start. You obviously want to show some character, but it’s not going to happen every time.”

P.K. Subban was a star again, scoring a goal with an assist. The Montreal defenseman also may have gotten away with a no-no with about 10 seconds left when, without anyone near him, he skated directly into the goal post, knocking the net off its moorings. The puck then came around to Krug at the right point and the B’s could have had a scoring chance, but the play was whistled dead. A penalty shot could have been called for Subban dislodging the net, but the officials elected to view it as an accident.

“After (Subban) rimmed the puck, Torey got the puck and he found me. I had so much room in front of me, I could have walked in. You never (know) what can happen with 8-10 seconds left,” David Krejci said. “Yeah, it was frustrating at the time, but I don’t know if that was a penalty or not.”

Said Bergeron: “He’s playing the clock and he’s trying to make something happen. Maybe he felt that we were coming hard. You’ve got to leave it to the refs, and they didn’t make the call. But it’s about bearing down and starting a lot earlier to make it a game.”

As debatable as the non-call might have been, this game was hardly a case of the Bruins getting jobbed by officials swayed by the rabid Bell Centre crowd. Referees Tim Peel and Chris Rooney let the teams play and the game was better for it. Each side was awarded one power play, the B’s coming in the first period on a Subban roughing penalty and the Canadiens’ when Carl Soderberg clobbered Price in the third period.

No, the culprit in this loss was staring the Bruins in the mirror. The B’s were far too sloppy in their own end, especially early in the game, to escape with a victory.

Things started to unravel at 10:57 of the first. Rask came out to play the puck and a handoff to defenseman Kevan Miller went awry. It became a battle for the loose puck along the wall and Michael Bournival eventually played it around to Subban at the right point. Subban left a nice drop for Thomas Vanek, who made a great pass down to a wide-open Tomas Plekanec for the goal.

“I thought (Rask) was going back to Krug. We had more time than we thought and he came over to my side. Just a little bit of a miscommunication,” Miller said.