If the Bruins miss the playoffs by a point, they have another game to look back on and rue.

The B’s blew a three-goal lead, squandered a Pavel Zacha hat trick, lost another one-goal lead in the third period and lost 5-4 in overtime Sunday to the Pittsburgh Penguins, who were playing without (Sidney Crosby) and Evgeni Malkin (suspension).

The B’s were cruising, up 3-0 in the second period when they threw the Pens a lifeline by giving them a lengthy 5-on-3. That got Pittsburgh in it, and they were in it to stay.

The game-winner was maddening. After David Pastrnak was knocked down away from the puck in a blatant interference, Tommy Novak used the open space and scored on the first shift in overtime, just 17 seconds in. Charlie McAvoy had turned the puck over to Egor Chinakhov after the B’s won the opening faceoff and the Pens wheeled around in the zone. Pastrnak was knocked down by Erik Karlsson and Novak was wide open for the goal.

“It’s man-on-man,” Pastrnak told reporters in Pittsburgh. “Obviously, the guy I didn’t cover stepped into my lane. To me, it’s interference. It wasn’t called so… We’ve been playing 3-on-3 a long time and these picks happen all the time. But to me, it’s clear he stepped in my lane. Didn’t get called and it cost us a point, unfortunately. At the end of the day, we won the faceoff and we shouldn’t have been in that position. And we were up 3-1 so, yeah, tough loss.”

But the Bruins never should have let it get away. They got a point out of it, but they suffered their seventh straight road loss.

As bad as the loss was, and it was as ugly as they come, coach Marco Sturm wanted to move beyond it quickly. At this stage of the season, there’s no time — or benefit — to wallow in it.

“It was just unfortunate,” said Sturm. “Having a two-goal lead going into the third and we were playing, overall, solid defense and you just give it up in the third period. Of course, not happy about that. But at the end of the day,  it’s a good point for us and we’ll move forward.”

The Bruins took a 3-1 lead into the third but the Pens evened it up with two goals in 33 seconds, both on stretch plays.

First, Ryan Shea sent a long indirect pass for Connor Dewar off the end boards. Dewar beat the icing to collect the puck and, with Jonathan Aspirot on him, he curled in the left circle and beat Joonas Korpisalo with a Crosby-like backhander at 6:02.

On the next shift, Anthony Mantha got behind Aspirot to accept Novak’s pass, moved in alone on Korpisalo and slipped the puck between the pads to tie the game.

Sturm had seen enough and called his timeout to calm his team.

It worked, briefly. Just 1:59 after Mantha’s goal, Zacha completed the hat trick when he took a good feed from Viktor Arvidsson and beat Arturs Silovs from the slot.

But the Pens kept coming back and they tied it again at 11:18 on Mantha’s second goal as he tapped in a the rebound off a Parker Wotherspoon shot.

Wotherspoon took a high-sticking penalty with 6:32 left. The Pens had a great shorthanded chance by Karlsson that Korpisalo stopped but the loose puck sat in the crease for Noel Acciari to knock home into the empty net but Pastrnak beat him to it to save a goal.

Both team had chances down the stretch, including one for Arvidsson in the final seconds that Silovs poked away to send it to OT.

The B’s did not come out strongly as they had several turnovers on breakout attempts and the Pens carried the play in the early going.

But Chinakov did the B’s a favor, tripping Marat Khusnutdinov in the Boston zone at 7:38.

After the B’s kept the puck in the Pittsburgh zone for most of the advantage, Morgan Geekie found Zacha with a great cross-ice pass and, from the right circle, Zacha blasted a one-timer for his second power-play goal in as many days. Zacha’s 17th of the season was also the first time the B’s had scored the first goal in nine road games. It was a crisp power play, something with which Sturm had not been thrilled about since coming out of the Olympic break.

That seemed to get the B’s into the game and they very nearly had a 2-0 lead. Arvidsson and Casey Mittelstadt had a 2-on-1 and, after Arvidsson made a nice move on the Pittsburgh defender, a 2-on-0. But Arvidsson’s pass was in Mittelstadt’s skates and the great chance went by the wayside.

The B’s took a 2-0 lead at 8:47 when Zacha’s goal total matched his uniform number.

After Korpisalo had made several good saves to preserve the lead, Zacha doubled it on a pretty play. Arvidsson found him in the slot and, after making a great fake on the Pittsburgh defender, Zacha lifted a backhander over Silovs’ glove.

Pastrnak came into the game riding an eight-game goal-less streak when his own hustle and a Silovs gaffe led to his 23rd goal of the season at 12:23. With Pastrnak bearing down, Silovs went behind his net to play the puck. Pastrnak stole it from him, came out front and tried to tuck it into the empty net. It was going wide, but the puck went off the scrambling Silovs and went in.

The B’s appeared to be in full control but then they took their first two penalties in quick succession, a questionable tripping penalty and a no-doubt slash on Hampus Lindholm that gave the Pens a 5-on-3 for 1:38. On the two-man advantage, Chinakhov’s wrister from the slot beat Korpisalo just under the glove.