Kris Letang’s overtime shot gets past Washington Capitals goaltender Braden Holtby for a power-play goal to lift the Penguins to a 7-6 win. (Gene J. Puskar/Associated Press)

For how often these two teams have played each other, for how competitive their games have traditionally been, for how they have dominated the rest of the league the past three years, it was fitting they needed extra time to determine a victor Thursday night.

Capitals forward T.J. Oshie single-handedly erased a two-goal deficit in 21 seconds to force overtime. But then 19 seconds in, Evgeny Kuznetsov was called for hooking Sidney Crosby, putting the Penguins on a four-on-three power play. Defenseman Kris Letang’s slap shot decided things, lifting Pittsburgh to a 7-6 win over Washington in a wild first meeting of the season.

The teams have combined to win the past three Stanley Cups, and they’re still testing themselves against each other; one will probably have to get past the other for another crack at the trophy.

“The last three years, you can argue we were the two best teams in the league,” defenseman Brooks Orpik said. “We just happened to beat each other in the second round. I don’t really see that changing much this year.”

The Penguins are the standard the Capitals are chasing. Washington has a stated goal of repeating as Stanley Cup champions, and Pittsburgh’s titles in 2016 and 2017 — both of which included second-round series wins over Washington — marked the first time a team went back-to-back in nearly two decades. The Penguins are still fuming that the Capitals were the team to oust them from the postseason in May, and Thursday night’s win was a small bit of revenge.

“They’ve done something that we’re trying to do,” Capitals Coach Todd Reirden said before the game. “Just as much as that’s something that they want to focus on trying to be better at and get back something that was theirs, we’d like to duplicate something they’ve done in the past.”

Past Capitals trips to Pittsburgh have resurrected bad memories of past playoff disappointments, the Penguins’ Stanley Cup banners reminders of opportunities lost. But as Washington reviewed its most recent video from playing against Pittsburgh, it took pleasure from watching for a change. The last time the Capitals were in PPG Paints Arena, Kuznetsov scored on a breakaway in overtime of Game 6 to put them in the Eastern Conference finals for the first time in 20 years.

“It’s always a test, now maybe even more so than before because we both have a championship now,” Oshie said. “It’s a lot different coming into this barn having just won than them having just beat you.”

But playing a second game in as many nights, the Capitals were shaky at the start. Penguins defenseman Jamie Oleksiak scored through a moving screen in front of goaltender Braden Holtby in the first two minutes. Seventy-nine seconds later, Washington forward Andre Burakovsky had a defensive zone turnover, and with the puck suddenly on his stick, Pittsburgh center Sidney Crosby charged the net. Holtby was aggressive, skating up to make a toe save on Crosby’s backhand chance.

That seemed to steady the Capitals. Less than 30 seconds later, center Nicklas Backstrom shot a puck hard at the boards, and Jakub Vrana punched in the rebound to tie the game. Less than a minute later, Orpik improbably scored with a slap shot that beat Penguins goaltender Matt Murray. That was Orpik’s first regular season goal since Feb. 26, 2016.

The frenetic scoring pace continued as the teams traded goals for a total of five in the first eight minutes of play . Washington had three off four shots, while Pittsburgh had one fewer in each category.

“You always, in back-to-backs, struggle a little bit with detail,” Reirden said. “Our commitment to playing defense was nowhere near to what we did [Wednesday night]. . . . But I’m really proud of our guys for being able to scratch and claw and tie that thing up and get a [standings] point out of here.”

When Reirden saw the Capitals’ schedule — a back-to-back set of games with Boston in Washington for the Stanley Cup banner-raising ceremony and then a game in Pittsburgh the next night — he knew he might have to play Holtby in both contests. Holtby never played both ends of a back-to-back last season, but he also had an experienced No. 2 goaltender in Philipp Grubauer to spell him.

Pheonix Copley has appeared in just two NHL games in his career, and while he probably will make his season debut in net against the New Jersey Devils next week, the Capitals plan to increase Holtby’s workload to start the season. He stopped all 25 shots he faced — and they weren’t particularly difficult to save — in Washington’s 7-0 win against Boston on Wednesday. He was peppered with 28 shots through 40 minutes in Pittsburgh. The Penguins finished with 41 shots.

“You can count all the real big saves that Holts made that he probably shouldn’t have even made on top of the goals he gave up, we didn’t give him much of a chance,” Orpik said. “In terms of why we gave them up, I don’t know if it was fatigue. We gave them a lot of room in the neutral zone, too, and if you do that against this team, they kill you.”

After the Capitals took a 3-2 lead into first intermission, Letang tied the game 30 seconds into the second period. Then 3:54 into the frame, Washington’s John Carlson scored on a two-on-one for his second goal in as many games. But Pittsburgh then pulled ahead with three unanswered goals until Oshie knotted it back up.

Until next time.