Capitals goaltender Braden Holtby turns aside a shot from Bruins left wing Jake DeBrusk, one of his 39 saves in a 4-2 win Thursday. (Elise Amendola/Associated Press)

TD Garden was the home of one frustrated groan after another Thursday night, something the Boston Bruins and their fans have grown accustomed to when the Washington Capitals are in town and Braden Holtby is in net. Thirty-nine pucks hit him and were turned away, and that soundtrack of lamenting one oh-so-close chance after another told the story of a game the Bruins arguably dominated but the Capitals won, 4-2.

Washington extended its mastery over Boston to 14 straight victories, and the team had Holtby to thank for this latest one. The Capitals are on a three-game winning streak, in first place in the Metropolitan Division with a four-point cushion.

“If we were to talk about one player that’s had a significant role [in the streak], we’d talk about Holtby,” Coach Todd Reirden said. “The impact that he’s had against this team has been definitely a difference maker.”

The Bruins controlled play for most of the game, and with the Capitals clinging to a one-goal lead to start the third period, Washington was assessed a bench minor for too many men on the ice, awarding Boston its fifth power play. David Krejci scored to tie the game at 2, and the Capitals were suddenly in jeopardy of losing their first game to the Bruins in nearly five years.

But just 69 seconds after Krejci’s goal, center Nicklas Backstrom calmly made his way down the ice on a rush before placing a shot just under goaltender Jaroslav Halak’s glove to put Washington back up.

The Capitals’ recent run of dominance against the Bruins has confounded even Washington players. Boston’s last win was in March 2014, two coaches ago for the Capitals, and though the Bruins struggled in 2014-15 and 2015-16, missing the playoffs in back-to-back years, they were among the league’s best teams the past two seasons.

“It’s nothing you think about,” Backstrom said. “You think about Boston as a great, top team and a hard team to play against and a hard building to come in here and play. Every time you play them, you know it’s going to be a tough game. It’s just fortunate for us that we’ve been able to be successful lately. . . .

“Holts was great back there, too.”

Holtby entered Thursday’s game 15-2-0 against the Bruins over his career with four shutouts, a 1.84 goals against average and a .943 save percentage. His first NHL win came against Boston in 2010, and Holtby’s breakout came in a 2012 seven-game playoff series against the Bruins. Just 20 minutes into Thursday’s game, Holtby again established himself as the best player on the ice when these two teams meet.

After the game, Holtby was bluntly asked, “Do you feel like you own the Bruins?” He chuckled and shook his head.

“We play pretty good hockey against them,” Holtby said. “We’ve had success against them, but they’ve always been good games. It’s just one of those things that seems to just happen, but they’re a fun team to play against. They work hard, and they battle, especially in tough areas. So I think that might be why we’re so engaged in the game when we play them, because they play a hard style of hockey every game.”

Holtby had 17 saves at first intermission, and six of those saves were on shots within 20 feet of the net. The Bruins also had two power plays. In a frame Boston dominated — the Capitals had just five shots in the opening period — Holtby was a brick wall in net.

Washington got an early lead when winger Jakub Vrana sneaked behind Bruins defensemen Torey Krug and John Moore and T.J. Oshie’s stretch pass sprung him for a breakaway. He scored two goals against Philadelphia two nights before, and his tally Thursday was his 15th.

As this series has grown lopsided of late, some bad blood has built, and the game got progressively feistier. Boston’s Brad Marchand instigated a fight with Washington’s Lars Eller in the season-opening meeting between the teams three months ago — Marchand took issue with how Eller celebrated scoring the seventh goal in a 7-0 Washington win — so Eller wanted retribution in the second period of Thursday’s game. Marchand declined the fight, and Eller was hit with an unsportsmanlike conduct penalty 7:43 into the frame.

“Everybody saw what he is,” Eller said. “I don’t think there’s a lot of integrity in his game.”

Said Marchand: “I haven’t looked at the stat sheet, but I really don’t feel like I need to prove anything. He plays maybe 10 to 12 minutes a night, and I’m playing 20. In a 1-0 game and to go on a power play, it doesn’t make sense.”

The Capitals withstood that power play, but the Bruins managed to crack Holtby for a first time when forward Ryan Donato took a pass from Krug and skated up to the right faceoff circle before ripping a wrist shot. Washington responded just 39 seconds later; Tom Wilson’s work along the wall set up Alex Ovechkin for his league-leading 31st goal. That gave Washington a 2-1 lead at second intermission, at which point Holtby had a whopping 27 saves through 40 minutes.

“I can’t tell you why he plays as good as he does and why there’s been a little bit more success here,” Oshie said. “He’s just a great goaltender.”

As the game got more physical and chaotic, Holtby remained poised in net, pivoting from one post to another as the Bruins launched more than 40 shots at him. Ovechkin’s empty-net goal in the final two minutes sealed it, and when the final buzzer sounded, Holtby’s stance in net finally relaxed as TD Garden emptied.