Outside the Washington Capitals’ dressing room, near the entrance to the visiting tunnel at Nassau Coliseum, forward Jason Chimera looked down at a small television and watched as if he needed further proof. They had survived the New York Islanders’ invasion, ceding 42 shots on goal, more than ever during the regular season. Down one forward because of injury, they had leaned on goaltender Braden Holtby, finally healthy after four days of weak muscles and misery. They had begun overtime hoping to silence this booming building. They left drenched in the din, stunned by a 2-1 loss.

So Chimera looked at the muted monitor, expressionless and lingering far longer than the 15 seconds New York needed to snatch a 2-1 series lead. The sequence looped once. There was Holtby, kicking one attempt to the side and jabbing another away. Twice. There was Islanders captain John Tavares, steaming toward the crease and hunting for a rebound. Three times. And now the puck, somehow squeezed behind Holtby’s back and past the knob of his stick, launching the towel-waving crowd into a frenzy while the Capitals slunk away, wondering how Game 3 of the Eastern Conference quarterfinals had disappeared so fast.

“I have no idea how it happened, what happened,” defenseman Matt Niskanen said. “Just . . . I don’t know. Kind of shocking actually.”

Across the carpet, at the locker stall nearest the showers, Holtby undressed and hosted teammates offering their condolences. Forward Tom Wilson gave a fist bump. Forward Joel Ward patted him on the back. The stomach flu that raged inside his body, sidelining him altogether for Game 2, had faded, but he faced another invasion Sunday afternoon. The Capitals were worked breathless deep into the third period, hammered in possession until center Nicklas Backstrom belted the equalizer. Only Holtby, their human defibrillator, their padded protector, kept them alive.

Soon, Holtby stood up and crossed his arms while cameras swarmed. Unlike Chimera, he hadn’t yet seen the replay of Tavares’s goal. Maybe he should have held defenseman Johnny Boychuk’s long-range attempt that zipped into his glove rather than slip it to defenseman John Carlson, who tried passing up the boards but instead returned possession to the Islanders. Maybe he could have slid closer toward the near post, guarding the tight angle, which Tavares later said he exploited. It was a tough loss to swallow, Holtby admitted, perhaps the toughest this season to date. But Game 4 lurked some 51 hours away. To avoid falling within one loss of elimination, the Capitals would need him then, too.

Tavares and the Islanders celebrate the goal that put them up 2-1 in the first-round series. (John McDonnell/The Washington Post)

“One of those things, you live and you learn,” Holtby said. “You make a split-second decision, hopefully it works out the best, and it didn’t there.”

With a roster suddenly thinned by injury, the Capitals needed every morsel of help from Holtby, who saved 14 shots during the opening period, only four fewer than his replacement, Philipp Grubauer, made overall Friday night. Right before Curtis Glencross’s penalty, New York forward Kyle Okposo crunched center Eric Fehr in along his left side. Fehr, who several years ago underwent a double shoulder operation, keeled over in pain, chatted with trainer Greg Smith on the bench and soon exited through the tunnel. He never returned.

“I expected that kind of start from them,” Coach Barry Trotz said. “We had to be better in the first than they were. We’ve just got to fix the battle in our game in the first period. But we survived it, and it was game on after that.

Inside the 13-minute mark of the second period, Okposo shanked one attempt wide of Holtby but circled around and trafficked in front. The puck scooted to the point, where defenseman Lubomir Visnovsky waited. Visnovsky had endured an injury scare earlier in the period after a hard hit and even absorbed a launching check from Alex Ovechkin on that same shift, but he now cranked forward Josh Bailey’s feed into traffic. With his back to the crease, Okposo deflected the puck and hooked it around Holtby’s blocker pad, then looked skyward and pumped both fists.

“That’s a goal that you want your guys to do, and we do that a lot,” Holtby said. “It’s pretty easy to put those behind you and focus on the next one.”

Then, deep into the third period, after the Islanders iced the puck and called a timeout to regroup, the Capitals pounced. A long shift from Ovechkin, Backstrom and defenseman Mike Green kept blue sweaters pinned inside their zone for almost two minutes, pelting pucks at Jaroslav Halak and chipping away. Finally, Backstrom flung a wrist shot through traffic from the slot, his second tying goal in two games. Ovechkin spun around and bolted toward the visiting bench, hopping off both skates, and his teammates followed suit. The group hug included everyone. They never celebrated again.

“We’ll pout about the loss probably for an hour here, then let it go,” Trotz said. “Have the right energy, the positive energy, the positive thoughts going forward.”