The Capitals’ bench celebrates their empty-net goal in the final moments — put into the Islanders’ net by one of New York’s players. (Al Bello/Getty Images)

It was a game of questionable calls and lucky bounces, the kind of things that tend to decide playoff games — and for a March matchup, this was pretty close. The Metropolitan Division’s top teams met Friday night, and the last time they had shared Nassau Coliseum was a playoff Game 7 in 2015.

On Friday, the Washington Capitals beat the New York Islanders, 3-1, to tie them atop the division, although New York still has a game in hand. With Islanders goaltender Thomas Greiss pulled for an extra skater late, forward Josh Bailey inadvertently put the puck in his team’s empty net, sealing the result for Washington. T.J. Oshie was credited with the tally at 18:32, capping a three-goal third period.

“We kind of felt going in that it was going to have a little bit of a playoff feel,” Oshie said. “Two teams with similar styles not giving up a lot. . . . We just kept pushing and found a way to get the win.”

It took the Capitals more than 43 minutes to get on the board, but they stayed patient and stuck to their game plan before Jakub Vrana broke through by punching a deflected pass past Greiss to tie the score at 1 with his 19th goal of the season.

Then on the next shift, Islanders captain Anders Lee was called for interference, awarding Washington its first power play. Just 13 seconds in, captain Alex Ovechkin scooped up the rebound of Oshie’s shot, and the puck fortuitously deflected off a New York stick before taking a high hop over Greiss and into the net for the go-ahead goal.

Ovechkin is on an eight-game point streak with seven goals and four assists in that span, and Friday’s was his league-leading 45th goal of the season. He has 10 career 45-goal campaigns, more than any other player in NHL history.

“I didn’t know about that,” Ovechkin said. “The guys told me. Yeah, it’s pretty special.”

The Capitals had allowed the first goal in their three games heading into Friday’s, and they did so again against the Islanders. Defenseman Dmitry Orlov made an ill-advised cross-ice pass exiting Washington’s zone, and it was picked off by forward Tom Kuhnhackl, who casually skated toward goaltender Braden Holtby and scored on a backhand 2:43 into the game. New York’s Leo Komarov appeared to be offside on the play, but the Capitals didn’t challenge the goal.

That’s because the play was considered a delayed offside, and a near-identical scenario was upheld against the Capitals in a game against the Minnesota Wild two years ago. On the zone entry, the puck was indeed across the blue line before Komarov tagged up — and it was on the linesman to blow the play dead at that time — but Kuhnhackl never touched the puck as it went across the line. Komarov then tagged up and made the play onside. In an intermission interview with MSG Network, Kuhnhackl acknowledged that he thought the play was offside.

“I knew it was close, but I kept kind of playing it,” Holtby said. “And then he stopped skating. Our guy stopped skating. The crowd went silent. It just kind of froze me a little bit. I didn’t know what was going on. It was a strange play; it almost looked like he thought the whistle had blown or something. It was weird. Luckily, it didn’t hurt us.”

The teams met in Uniondale for the first time since that 2015 playoff series — won in seven by the Capitals — because the Islanders are splitting their games this season between Brooklyn’s Barclays Center and Nassau Coliseum while their new arena is being built at Belmont Park. That won’t open before the 2021-22 season at the earliest, but New York has made the top of the division its home this year.

The Capitals and Islanders have been side by side in the Metropolitan for a while now, and while Washington was expected to be one of the league’s better teams after returning the bulk of its Stanley Cup-winning roster from last season, New York’s rise has been unexpected. That’s a credit to Barry Trotz, coach of the Capitals the previous four seasons before moving to the Islanders’ bench in the offseason. New York has gone from the team that allowed the most goals per game last year to the best defensive team in this one, and while Washington was facing the Islanders’ No. 2 goaltender, Greiss entered with an impressive .928 save percentage and a 2.26 goals against average.

He stopped all 19 of the Capitals’ shots through two periods. Washington had been shut out in its previous game against New York, a 2-0 loss Jan. 18 in Capital One Arena, and this game was similarly tight, with both teams struggling to get time and space. Holtby faced just 13 shots through 40 minutes, but two pucks clanged off the pipe behind him. He finished with 20 saves.

“It was an extremely competitive game,” Coach Todd Reirden said. “I thought the intensity level was at a high, and you know what, we didn’t have success to start the game, but we stayed the course. We didn’t change how we played. We continued to play the same way the rest of the game until we were rewarded. That’s a big step in our overall growth of our group.”

It was around this time last season that the Capitals tuned up their defensive play before the playoffs, when their suffocating style became their identity. Reirden said he has been more concerned with getting his team back to that than monitoring how other teams are faring, but entering Friday, just five points separated Washington and the Pittsburgh Penguins, who were just barely out of postseason position.

The Capitals could use some cushion in the standings, and they didn’t waste an opportunity to get just that. They now have a five-point edge on the third-place Carolina Hurricanes, and they’re six ahead of Pittsburgh and the Columbus Blue Jackets.

“You can see that everybody right now play well and play hard because we know that at this time of year, everybody have to step up and play the same way like we did last year,” Ovechkin said. “We have experience that help us, and we’re growing up as a group.”