This was not the postseason debut the Yankees bullpen was looking for.

From Luke Weaver blowing a one-run lead in the seventh, to David Bednar allowing an insurance run in the ninth, Yankees relievers weren’t as sharp as they’d been down the stretch — or enough to beat the Red Sox on Tuesday in The Bronx in a 3-1 loss in Game 1 of their wild-card series.

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Weaver, who enjoyed a breakout season that was cemented by a tremendous performance in the playoffs a year ago, couldn’t replicate his October magic.

This past year has been rockier for the right-hander and his postseason got off to a much rougher start, as Weaver entered with one out in the top of the seventh, with the Yankees up 1-0.

Weaver replaced Max Fried — who got Jarren Duran for the first out — and faced Ceddanne Rafaela, who’s given Weaver fits in the past.

In seven plate appearances against Weaver, Rafaela was 2-for-6 with a pair of homers, a walk and three strikeouts.

But Aaron Boone went to Weaver against the bottom of the lineup and after Weaver got ahead 0-2, he ended up walking the center fielder after Rafaela fouled off five pitches in the 11-pitch plate appearance.

“Just a really good at-bat,” Weaver said of Rafaela. “He’s had some really good at-bats in the past. It’s gone both ways.”

In the biggest spot, though, Rafaela won — and the Yankees were on their way to a loss.

“That’s a real tough one to swallow, when you know you have him at an advantage count,’’ Weaver said. “He did a really good job spoiling some pitches and the next thing you know, it’s 3-2. He did a good job battling through. I didn’t want to give in and throw a cookie.”

But after the walk, Weaver said, “The momentum kind of switched.”

Nick Sogard followed with a double that sent Rafaela to third, before pinch-hitter Masataka Yoshida changed the game with a two-run single to end Weaver’s rough night.

He allowed all three batters he faced to reach, a stark contrast to his performance last October, when Weaver didn’t give up an earned run over 15 ¹/₃ postseason innings.

“I felt the outing overall was competitive,’’ Weaver said. “I was throwing to areas I wanted to, but they weren’t perfect. It never is. There are a lot of disappointed people, including myself.”

Bednar came in with the Yankees still down a run. After getting the first two batters, he allowed a single and stolen base to Trevor Story and then an RBI double to Alex Bregman.

The added run gave Aroldis Chapman more wiggle room when he loaded the bases with no one out in the bottom of the inning.