BOSTON — The Washington Capitals simply could not keep up with the Boston Bruins on Friday night in Game 4 of this first-round playoff series. The visitors looked lifeless, at least a step behind the blur of black and yellow sweaters at TD Garden.

The result was a 4-1 loss that left them on the brink of elimination, trailing this best-of-seven affair 3-1 with Game 5 on Sunday at Capital One Arena.

“This one, we just weren’t good enough,” Capitals Coach Peter Laviolette said. “We weren’t fast enough. We didn’t execute well enough.”

Should the Capitals fail to climb out of this hole, it would be the third straight season in which they were ousted in the first round since they won the Stanley Cup in 2018.

“We have to want it,” center Nicklas Backstrom said. “It’s obviously a big game coming up, and we have to be mentally ready. I feel like the previous three games before this we were a lot better than tonight. So we’ve got to be mentally ready, and we’ve got to play for each other. That’s maybe something we didn’t do tonight.”

Washington, a veteran team, simply looked older and slower than the Bruins on Friday. Multiple players also did not appear to be fully healthy. The Capitals were outshot 37-20 and dug themselves a 3-0 deficit after David Pastrnak and Charlie Coyle scored 34 seconds apart to open the third period.

Captain Alex Ovechkin responded with a one-timer that went off Brandon Carlo’s skate and past Bruins goalie Tuukka Rask 4:54 into the period. But the Capitals could not dent Rask any further.

Second-year netminder Ilya Samsonov, coming off a strong Game 3 performance that ended with a blunder behind his own net in double overtime, kept his team in it for the second straight game with 33 saves. But the offense in front of him sputtered.

“We just need five guys wanting to have the puck,” center Lars Eller said. “ … We’ve just got to support each other a lot better than we are right now, attacking with five, defend with five, play faster. Everything. Every aspect of the game, we’ve got to be better.”

Ovechkin’s goal came on the power play, one of seven for the Capitals. Boston was 3 for 5 with the extra man, with Matt Grzelcyk scoring with the man advantage with 5:10 remaining to push the margin to 4-1. After the game, the Capitals acknowledged the poor power-play performance, with Backstrom saying the team will have to “come up with something new.”

“I feel like they’re reading us pretty well,” Backstrom said. “So we can talk about that tomorrow and get better. We’ve just got to get some more shots and just create those secondary chances.”

Ovechkin’s goal was his second of the postseason — his 71st postseason goal of his career — and only the Capitals’ fourth goal from its top-six forwards in the series.

Samsonov was making his second straight postseason start and has yet to make three straight starts in his career. After a 40-save performance in Game 3, Laviolette went back to the Russian. Craig Anderson, who did not play in Game 3 because of what the team termed “body maintenance,” dressed as the No. 2 goaltender. Rookie Vitek Vanecek is still out with a lower-body injury suffered in Game 1.

Friday’s game took a chaotic turn in the second period. First, Samsonov appeared to get hit on his inner right thigh by Taylor Hall’s skate after Samsonov made a point-blank stop on Hall. Samsonov talked briefly with trainers on the ice but remained in the game.

Minutes later, Dmitry Orlov sent Kevan Miller to the locker room with a high hit. It appeared Miller’s head hit the ice hard when he fell. He did not return, instead going to the hospital for further evaluation. Orlov was originally assessed a major penalty, but it was changed to a double minor for roughing upon review.

With Orlov in the box, the Bruins opened the scoring when Brad Marchand deflected Pastrnak’s blast past Samsonov with 12 minutes left in the second period. Garnet Hathaway then was dinged two minutes for roughing Boston captain Patrice Bergeron, and the Capitals’ wheels started to come off.

“We can’t put ourselves down five, six penalties, whatever it was we had,” Eller said. “We’ve just got to be better in that department. More disciplined, don’t put ourselves in that situation.”

Making the loss especially tough for Washington was that Game 4 was the first time the Capitals have had all their skaters available in the postseason. Injuries, suspensions and covid protocols had Laviolette mixing and matching for more than a month, but Eller’s return had the Capitals back at full strength.

Washington had no shots on goal in the final 11:21 of the first. The Capitals had just four shots on Rask in the period.

The Bruins, meanwhile, had a spark from the start. With aggressive forechecking and high-danger chances, Boston was able to sustain offensive zone time and get pucks past the interior of the Capitals’ defense. Coyle came inches from giving the Bruins an early lead after his shot rang off the post with nine seconds left in the first. He found redemption — and the insurance tally in the third.

“It’s disappointing and a little frustration as well,” Backstrom said. “But at the same time, it’s not over. So we’ve just got to regroup here and then we’re going back home here, so hopefully we can have a good meeting [Saturday] and talk about stuff we can do better.”