NEW YORK -- As soon as Edwin Díaz walked off the Citi Field mound in the eighth inning Sunday night, Mets manager Carlos Mendoza approached him to say he wanted Díaz to pitch the ninth, as well.

“We’ve been protecting him the whole year,” Mendoza explained afterward. “And now it’s big boy time. He’s our guy.”

Díaz, who had given the Mets a four-out save only one day prior, had never previously done anything like this in career. He had never recorded six outs the day after pitching in a game, period, let alone one in which he had extended himself for more than an inning. But he wanted the chance. As the Mets batted in the bottom of the eighth, Díaz stalked through the clubhouse, drinking water and keeping his body warm.

Then Díaz returned to the mound to lock down a victory. Striking out Kody Clemens to strand the tying and go-ahead runs in scoring position, Díaz earned perhaps the most significant save of his Mets career in a 2-1 win over the Phillies, making his team a heavy favorite to earn a playoff berth.

To clinch a National League Wild Card spot, all the Mets need to do now is take two of three from the Braves this week in Atlanta. (In this scenario, they’d be up three games on the Braves with three to play, but have clinched the tiebreaker against the Braves this week.) Even if they lose two of three, they’ll still control their own destiny heading into the season’s final weekend. They also own the tiebreaker on Arizona, and are tied with the D-backs in the standings for the second Wild Card spot.

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“This is playoff atmosphere and playoff baseball,” said outfielder Brandon Nimmo, who hit a go-ahead home run off Zack Wheeler in the sixth. “You just see how much more every pitch means in these games. It carries so much weight, and these guys are rising to the challenge.”

Nimmo’s blast, which barely eclipsed the right-field fence, gave the Mets the lead they desired. But Mendoza still needed to coax nine more outs from his bullpen after limiting starter Tylor Megill to four innings. Phil Maton had already given the Mets a max effort of his own, allowing some hard contact but zero baserunners in the fifth and sixth. From there, Mendoza turned to José Buttó, who struck out a pair in the seventh.

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With the potent top of Philadelphia’s lineup due up after that, Mendoza knew he wanted to go to his best reliever. Díaz responded by striking out Kyle Schwarber and Bryce Harper en route to a scoreless eighth.

That’s when “the manager came to me [and said], ‘We need you in the ninth,’” as Díaz recalled it. “I said, ‘I’m ready. I’m ready to go.’”

But it was not easy. Clearly laboring, Díaz walked Bryson Stott and Brandon Marsh and allowed them to steal three bases without much resistance, setting up a showdown against Clemens with two men in scoring position. At that point, a sold-out crowd of 43,139, which had given Pete Alonso standing ovations all night in anticipation of this being perhaps his final home game in Flushing, ratcheted up its volume.

When Díaz finally blew a 98 mph fastball past Clemens to end things, the crowd reached nirvana.

“Just unbelievable, right?” Nimmo said. “You’re asking a guy to go out there and go through the toughest part of the NL East-leading Phillies, and they have superstars all through that lineup, and you’re asking him to go through there and not give up one run. It’s a tough thing to ask. But if anyone’s up for it, Díaz is. Just what a beautiful story for him.”

It’s a story that, in many ways, began when Díaz tore the patellar tendon in his right knee during the 2023 World Baseball Classic. He missed that entire season, and although Díaz reported to Spring Training ’24 completely healthy, the Mets bubble-wrapped him for the early portion of this year. A right shoulder injury in May complicated matters, and as recently as late August, Mendoza was still treading carefully with his top reliever.

But not any longer. Not at what Maton called “a tough time of year to be a closer,” when managers tend to ask for more, more, more -- often more than a pitcher has ever given before. That was the case Sunday. And it will continue to be the case going forward.

About a half-hour after Sunday’s win, Díaz was already preparing for the Atlanta series, conducting an interview with a blood-flow restriction cuff wrapped tightly around his arm. Asked if he will be available for the start of that set, Díaz did not hesitate.

“I’ll be ready for Tuesday,” he said. “These are playoff games. We [have been] playing playoff games since early September. I’ve got to be ready every single day, and I know I will be ready on Tuesday.”