Finally greeted by the stakes they’ve longed to have back since the mundanity of regular-season hockey set in six months ago, and matched with the proverbial happy-to-be-here opponent, the Avs played with their seafood.

A team that never trailed a series en route to the 2022 Stanley Cup now finds itself swimming against the current in the first round.

The Seattle Kraken proved to be more than plucky Tuesday night at Ball Arena, stealing Game 1 of the playoffs 3-1 from the Avalanche. It completed an underdog sweep to ring in the postseason: All four higher-seeded teams in the Western Conference lost Game 1 at home.

“They were one step ahead,” Cale Makar said.

“They’re a good hockey team. We knew that coming in,” fellow defenseman Bo Byram told The Post. “And it’s a seven-game series. There’s no reason to hang our heads or get down. It’s one game. We’ll just refocus.”

The Avs were 4-0 after a loss in last year’s playoffs. But the defending champs had also won six consecutive playoff series Game 1s before Tuesday. They entered this postseason on a blistering eight-game point streak to win the Central Division and earn the Seattle matchup. But the wild card Kraken pounced early in the first and second periods, and the Avalanche couldn’t cash in on two power play opportunities while trailing.

“I didn’t like our execution. That was probably the first thing that stood out to me, in a lot of areas of the ice,” Avs coach Jared Bednar said. “Not just on our attack.”

Mikko Rantanen scored on a Nathan MacKinnon assist and Makar buzzed in his return to the lineup after missing seven games. Other than that, Colorado got little help lower in the lineup against a Seattle squad that lives and dies on depth.

“I think we weren’t sharp enough mentally,” MacKinnon said. “Physically I think we were there. We were playing hard. It’s just, we’ve got to make plays with our forecheck, and they’re a tough team to create (against). … But we still had the puck on our stick a lot to execute, and for whatever reason we couldn’t make those plays.”

The Kraken scorers were all middle-six forwards. Artturi Lehkonen, J.T. Compher and Valeri Nichushkin lost their matchup; they were on the ice when second-line counterparts Alexander Wennberg and Morgan Geekie scored for the Kraken.

Meanwhile, Game 1 demonstrated again that depth is a snowball for the Avalanche.

Andrew Cogliano didn’t play as he’s still dealing with an upper-body injury sustained last week. That meant Ben Meyers was in as a third-line wing, making his playoff debut a year out of college but only playing five minutes. Responsibility was exponentially on the top players, and it will become more so as the Avs play from behind in the series.

The playoffs started with a wrinkle for Bednar. With a surplus of healthy defensemen in the lead-up to Game 1, he was confronted with a difficult lineup decision for what felt like the first time all season, after months of injuries making the choices for him. Which veteran would be scratched: Erik Johnson or Jack Johnson? The latter participated in line rushes. He was set to play, and Erik Johnson was set to sit.

The longest-tenured Avalanche player was even officially designated a scratch — until moments before puck drop when Jack Johnson was ruled out with a lower-body injury sustained while warming up. In went Erik.

It was almost as ominous a precursor as what happened next. The reliable Devon Toews made a rare gaffe early in the first period, giving away the puck behind the net to unwittingly assist the first playoff goal in Kraken franchise history. Eeli Tolvanen (third line) scored it. There wasn’t much goalie Alexandar Georgiev could do in his first playoff start to defend the point-blank chance.

Former Avs goalie Philipp Grubauer, a weakness for the past two seasons in Seattle, put together a gem in the other net. He saved 34 shots after finishing under a .900 save percentage this season. When he wasn’t brick-walling his old team, the Avs were wincing at puck luck. Down 2-1 in the second period, defenseman Bo Byram clanked the crossbar. It was the last truly threatening chance for the Avalanche.

But when MacKinnon was asked what he saw from Grubauer in the stalwart performance, the Avalanche center responded: “Nothing.”

“He was here a while ago,” Byram said. “I don’t know how many guys are left from those teams, but we’ve got a really good goalie, too, so we like our matchup for sure.”

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