The Washington Capitals spent most of the regular season doing things the hard way. Yes, they were dominant in the win column and secured their spot in the Stanley Cup playoffs before anyone else, but they also led the NHL in comeback wins.

It came as little surprise, then, that the Capitals did things the hard way in Game 1 against the Montreal Canadiens on Monday night at Capital One Arena. Their two-goal lead after two dominant periods evaporated in the final 10 minutes of regulation. It took captain Alex Ovechkin’s first career playoff overtime winner to lift Washington to victory, 3-2, 2:26 into the extra period. Game 2 is Wednesday night.

Ovechkin scored two of the Capitals’ three goals and had the primary assist on the other.

“I thought he made a couple big plays for us tonight,” Washington Coach Spencer Carbery said. “Was physical, set the tone. He was leading the charge and dragging guys into the fight.”

Goaltender Logan Thompson, whose status for the game was a thinly veiled mystery, returned from the upper body injury he suffered April 2 to make 33 saves in his first playoff start for the Capitals. Samuel Montembeault stopped 32 of 35 for Montreal.

“It’s good,” Thompson said. “It was fun. I missed being in the room and being around it. I missed a decent chunk of time. It sucked not being around.”

“I decided that Logan has had a phenomenal year and deserved to start Game 1 of the playoffs for us,” Carbery said.

The Capitals looked lethargic at times as they played out the string at the end of the regular season and counted the days until Game 1 arrived. When the puck dropped to begin the playoffs, their switch flipped immediately.

Anthony Beauvillier and Ovechkin laid bruising hits in the first 20 seconds, two of the 20 hits Washington racked up in the first period alone. Ovechkin led the way with four, making his mark physically from the beginning.

The physical, aggressive start fed into the crowd’s energy and built a sense of anticipation within the arena, but the Capitals couldn’t find a way through Montembeault in the early going. Montreal pushed back in the middle part of the first period, aided by a power play granted when winger Taylor Raddysh slashed Patrik Laine. Thompson made three saves on the penalty kill, including a flashy glove stop on a one-timer by Laine from the left circle that showed off Thompson’s joy to be back between the pipes.

Washington earned its first power play from a scrum behind Montembeault, one of many not-so-friendly meetings between the two teams throughout the night.

And with less than two minutes left in the first period, Ovechkin finally gave the crowd what it had been looking for since the game’s first few shifts. As the Capitals entered the offensive zone on the power play, Ovechkin caught a pass from winger Tom Wilson and fired it through defenseman David Savard’s legs, using Savard as a screen to fool Montembault and beat him over the blocker.

The physicality quieted — slightly — in the middle frame as the Canadiens tried to use their skating to pull Washington apart in transition. But the Capitals stayed contained within their structure, still laying hits when the opportunity presented itself, and didn’t get drawn into the back-and-forth track meet Montreal wanted to play.

Just under eight minutes into the period, Beauvillier popped loose and skated in alone on Montembeault. His first attempt missed, but as he followed up the puck behind the net, he forced Lane Hutson into a turnover to keep the play alive. Center Dylan Strome tapped a backhand pass to Ovechkin as he came onto the ice, and Beauvillier recovered to the net front to tip Ovechkin’s shot past Montembeault to double Washington’s lead.

Montreal’s Brendan Gallagher nearly halved the deficit in the final seconds of the second period, after Hutson forced a turnover on an attempted breakout and Gallagher had a look from a sharp angle to Thompson’s left. But Thompson made the stop with 21 seconds left in the frame, enough for the Capitals to take a 2-0 lead into the dressing room through 40 minutes.

In the third period, Washington seemed content to sit back and defend its lead, then couldn’t get back into gear when the pressure came.

“We can’t sit back,” Strome said. “We’ve been a great third-period team all year, regardless of if we have the lead or not. I think we know better than that.”

A tripping penalty on Dubois with 9:57 remaining gave the Canadiens their second power play of the game, at a critical moment for Washington to keep its grip on the game. Montreal had just two shots on goal in the first 10:03 of the period before the power play.

The Canadiens needed just 29 seconds to take advantage of the opportunity. Thompson slid over to cover Laine in the left circle, but Laine’s shot deflected off Dowd at the net front and bounced to Cole Caufield with half of the net wide open for the finish.

The tension ratcheted up as Montreal kept pushing. After dominating in possession and scoring chances the majority of the game, Washington found itself back on its heels in the final minutes. The Capitals turned nervous and looked out of sorts; the tying goal began to feel inevitable.

“I thought we started to overcomplicate it a little bit,” Carbery said. “We got away from it. … You look at how the second goal, go back to that film, watch a few sequences before, you can see it coming. You can see it because there’s a couple mismanagement of plays that end up leading to bad things.”

A turnover behind Thompson with just over four minutes left to play led to a chaotic sequence in front of him, and Washington couldn’t get control of the puck and get it out of danger. And when Thompson slid too far across his crease, leaving the net open again, Nick Suzuki was in the low slot to put it home and tie the game.

The Canadiens pushed to win the game in regulation in the final seconds, but the Capitals held on to take it to overtime. Montreal outshot Washington 14-7 in the third period and led 32-16 in shot attempts, emblematic of its dominance in the final 10 minutes to even things up.

When overtime began, the Capitals were back to the dominance they showed in the first 40 minutes, and they needed less than three minutes to make the victory stick. Beauvillier set up Ovechkin for the winner, capping off a standout night for their line — and Ovechkin.

“Good character on us to just go into overtime and leaving that stuff that happened in the third period behind us,” Beauvillier said. “Just getting back to being aggressive.