Buck Showalter and his culture held up after all. Under extreme duress, on the brink of disaster, Showalter’s Mets showed up at Citi Field on Saturday night to win a sudden-death playoff game, one night after they did not bother to show up at all.

Four wild-card teams faced elimination on this day, and only one lived to tell about it. Showalter’s.

And after his Mets had defeated the Padres by a 7-3 count, the winning manager wanted to talk about the poise his players showed in staying within themselves with the stakes as high as they were.

“It’s so easy to get out of it,” Showalter said. “It takes a lot of discipline. … Sometimes less is more, and that’s hard to do.

“It’s a real tribute to the players.”

And to the manager who prepared them to face and ace this manhood challenge.

For all his homespun stories and off-schedule filibusters designed to divert his audience from the urgent issues of the day, Showalter had to feel the heat before this one. He is universally respected for his baseball acumen, his extreme attention to detail, and his ability to mold and inspire teams over the six-month regular-season grind.

He is also known as a manager with a 9-15 postseason record, and as a 66-year-old lifer who has never advanced to the World Series.

Showalter has suffered some brutal playoff losses in his day, including the epic Game 5 loss to Seattle as the Yankees’ manager on Saturday’s date, Oct. 8, 27 years ago, in the 11th inning in the Kingdome. A Mets catcher name Todd Pratt once eliminated his Diamondbacks with a 10th-inning Game 4 homer in the ’99 NLDS that would go down as one of Pratt’s two career postseason hits.

Both hurt, though the 1995 loss to the Mariners — Showalter’s last game with the Yankees — hurt a lot more. He would later compare watching a tape of that game to “watching ‘Brian’s Song’ with the lights off.” He was familiar with that kind of pain.

Truth is, a loss to San Diego wouldn’t have inflicted irreparable damage to Showalter’s legacy, not in his first season running the Mets. Though his team blew a division title it had no business blowing, Showalter & Co. won 101 games — the second-most in franchise history — while missing Jacob deGrom and Max Scherzer for significant portions of the season. And besides, Steve Cohen said he’d be disappointed if the Mets didn’t win a championship within his first 3-5 years as owner.

He didn’t say within his first two to five years as owner.

But still, going down in two straight at Citi Field to the 89-win Padres would have left a painful, purple bruise on Showalter’s program. He seemed to understand this when fielding questions before Game 2, when he acknowledged that a player or manager “can want something too much,” and when he described anxiety under big-game pressure as a noble human reaction.

“It’s like if somebody says, ‘Is somebody’s pressing?’ ” Showalter said. “I hope so because that means you care.”

Deep down, did his comments suggest that the manager wanted this too much? Did they suggest that he was pressing?

Just like he knew he’d be criticized for not scheduling deGrom as his under-all-circumstances Game 2 starter, Showalter knew he would take incoming fire for dusting off Darin Ruf and making him his designated hitter over Francisco Alvarez. And yet he did it anyway. He knew he would take incoming fire for summoning Edwin Diaz in the seventh inning — and for bringing him back in the eighth after the Mets took 45 minutes to break the game open — if things went sideways. And yet he did it anyway.

If nothing else, Showalter doesn’t fear the consequences of failure. He explained that Ruf had an encouraging track record against Blake Snell and the Padres, and that Alvarez gave him more flexibility on the bench. It sure wasn’t pretty, but Ruf did reach base twice — on a walk that came via a tough, full-count take, and on a hit-by-pitch.

With the Mets holding a 3-2 lead and still needing nine outs to seal it, Showalter called for his best player, Diaz. Six years ago, he never called for his closer, Zack Britton, in an 11-inning wild-card loss to Toronto, despite the fact that Britton had posted a 0.54 ERA that year. Showalter wasn’t going to wait on his indomitable closer this time.

After he patted deGrom on the ass and thanked him for his work, Showalter charged Diaz to attack Trent Grisham, who had already homered off Scherzer on Friday night and off deGrom on Saturday night. Grisham would have won a newfangled Triple Crown if he homered off Diaz, but could only manage a ground ball to first.

The closer got Showalter five outs, then passed the ball to Adam Ottavino, who had to pass it to Seth Lugo to get the final out with the bases loaded and the tying run at the plate. Lugo got Josh Bell to hit a benign grounder to first, and the home team finally exhaled.

Showalter’s culture of professionalism and accountability held up. And because of that, his Mets will play the Padres in a Game 3 that will feel like a Game 7.