WASHINGTON — Rick Nash led the Rangers with 42 goals this season but had yet to find similar success in postseason play. Nash scored just once in the team’s first 10 playoff games and not at all through the first five games of this second-round series against the Washington Capitals.

Nash finally ended that frustration with a crucial goal in Game 6 on Sunday night. He scored 54 seconds into the third period to give the Rangers a two-goal lead on a night when they finally showed some punch on offense and tied the series at three games apiece with a 4-3 victory over the Capitals.

In his first 10 postseason games, Nash registered one goal and five assists. That included just two assists in the Washington series, and relief was easy to hear in his voice when he talked about that goal afterward.

“It’s nice to score goals,” Nash said. “Obviously, they’ve been hard to come by. It’s been really frustrating when you can’t do the thing you’re supposed to do and you feel like you’re letting your team down. It weighs on you.”

Rangers Coach Alain Vigneault brushed off any possible criticism of Nash, saying he had been helping the team in many ways in this series.

“He’s been playing well,” Vigneault said. “Anybody that’s really followed this series at both ends of the rink will tell you that he’s been an effective player. But he’s an offensive guy that is noted for his scoring, and tonight he came up real big for us at an important time.”

The Nash goal proved crucial because of its timing. Chris Kreider stunned the Capitals with a goal 40 seconds into the first period and made it 2-0 when he tapped in a rebound with less than a second left.

But the second period belonged to the Capitals, who outshot the Rangers, 18-4, and repeatedly threatened. They got a Jason Chimera goal in the first minute that cut the lead to 2-1 and kept the Rangers on their heels for much of the period, but goalie Henrik Lundqvist made 17 of his 42 saves in those 20 minutes to keep the Rangers in front.

Nash then made it 3-1 with his goal early in the final period. He eluded Nicklas Backstrom deep in the Capitals’ zone, made a good fake and quickly slipped the puck past goalie Braden Holtby. That defused any momentum the Capitals had coming into the third.

Dan Boyle then added another goal at 4:24 for a 4-1 lead before the Capitals made a furious rally in the final 11 minutes that the Rangers withstood.

The Rangers finished with 28 shots on goal but found a number of good scoring chances, especially in the first period, when they put 20 shots on goal. Asked to explain the offensive outburst after his team had scored just seven goals in the first five games, Vigneault just shrugged and held up his hands.

“I don’t have an explanation,” he said.

Kreider had a similar reaction when asked the same question in the locker room. The Rangers simply kept up and pressure and, finally, got some pucks past Holtby.

“Probably wasn’t our best game of the series by a long shot,” Kreider said. “It might have been our worst game. Pucks just happened to go in. That’s the way hockey works.”

The question now is whether the Rangers can bring that kind of offensive performance to Game 7 on Wednesday at Madison Square Garden.

Nash said he felt better scoring goals, but in the end, he only wanted the Rangers to win. They did that in this game, and Nash smiled when talking about how he broke his dry spell and helped his team for a deciding game.

“It’s tough, but all that matters is winning games,” Nash said. “That’s all that matters is the win and going into Game 7 with some momentum. It’s a momentum swing.”