The Bruins head into the three-day Christmas break with their best gut-check win of the season.

After losing David Pastrnak (upper body) in the second period and then surviving a third period five-minute major to Oliver Wahlstrom, the B’s got third-period goals from Elias Lindholm and Charlie Coyle to knock off the best team in the National Hockey League, grinding out a 4-1 win over the Washington Capitals at the Garden.

Brad Marchand assisted on the go-ahead and insurance goals and then added an empty-netter.

The B’s allowed just 11 shots on net, handing the Caps just their ninth regulation loss of the season.

The B’s took a 1-0 lead late in what had been a somewhat low-event first period as both teams did a good job protecting the front of their respective nets.

Washington got the first power play of the game, but the B’s did a good job of killing it off. When Martin Fehervary rammed Pavel Zacha from behind and was called for boarding, the B’s cashed in on their first PP chance.

After the first unit had a few cross-seams get picked off, the more direct second unit got the B’s on the board. Morgan Geekie simply snapped a shot from the top of the right circle that Charlie Lindgren stopped but Justin Brazeau was there to backhand home the rebound with 48 seconds left in the period. It was Brazeau’s seventh of the year and snapped an eight-game goal-less streak.

The B’s held a 6-3 shot advantage in the first.

But the Caps would get even early in the second after Tom Wilson drew an interference penalty on Brandon Carlo, a call the defenseman thought Wilson helped along.

The B’s were in the process of again doing a good job of killing it off until, with 10 seconds left on the minor, Jakub Vrana whistled a one-timer rocket over Jeremy Swayman’s glove shoulder and just under the bar at 4:50.

That was it for fireworks in the second as the game slogged along at a low hum. The B’s held a 7-4 shot advantage in the second. The game was deadlocked at 1-1, but the B’s had their work cut out for them in the third. Washington was plus-18 in their third periods this year.

What was worse, the B’s lost David Pastrnak in the second period. He played only four shifts in the period. On the second to last one, he pulled up to avoid a hit from Wilson and didn’t look right after it. He took one more shift that lasted 23 seconds and that was it for him for the night.

In Pastrnak’s absence, Oliver Wahlstrom was elevated to the top line and just 10 seconds into the third, Wahlstrom picked up a five-minute major penalty and the gate when he ran Fehervary into the end boards. It was reviewed and held up.

But the B’s did a masterful job of killing it off, allowing just one shot to get to Swayman.

After a 4-on-4 situation, the B’s got a power play when Trevor van Riemsdyk held Elias Lindholm and they had one good chance when Charlie McAvoy grazed the post from the high slot.

But the B’s did take the lead with 6:19 left in regulation on a pretty looking play. From the defensive zone, Charlie Coyle flipped a puck out high to Elias Lindholm at the Washington blue line. Lindholm pushed it to a rushing Brad Marchand and they had a 2-on-1. Marchand fed it back to Lindholm, who made a great move to his backhand, faking Lindgren out of the picture and scoring into the empty net.

It was Lindholm’s sixth of the year and it extended Marchand’s point streak to 10 games.

With the Caps pressing, the B’s broke out on another odd-man rush and got the insurance goal. Marchand hit the post and, though everyone in the building thought he scored, Coyle stayed with the play and scored on the rebound with 4:01 left in the third.