PHILADELPHIA -- For Mets manager Carlos Mendoza, one of the most important conversations of each day is the one with his closer. For five and a half months, the Mets treated Edwin Díaz carefully, not wanting to overtax his surgically repaired right knee nor his golden right arm. That changed almost overnight in late September, when Mendoza began asking Díaz for more, more, more.

Until Sunday, Díaz had responded in precisely the way the Mets hoped -- consistently telling Mendoza he feels great, passing all of the training staff’s testing protocols, and backing it up with his performance on the field. But in one of the highest leverage spots of the season in National League Division Series Game 2, Díaz cracked to let the Phillies back into a game they later won, 7-6, on a Nick Castellanos walk-off single against Tylor Megill.

The defeat evened the NLDS at one game apiece, with Game 3 scheduled for Tuesday at Citi Field -- the Mets’ first home playoff game in two years.

“Obviously, it feels horrible,” Megill said. “We lost. Walk-off. Not the way we wanted it to go.”

After Brandon Nimmo gave the Mets the lead with a solo homer in the seventh at Citizens Bank Park, the Phillies rallied in the bottom of the inning against reliever José Buttó. With two men on base and two outs, Mendoza went directly to Díaz to put out the fire, which he did with a strikeout of Kyle Schwarber.

But an inning later, Díaz issued a one-out walk to Bryce Harper, which he derided as “lazy” because of his unaggressive approach, then a single and finally the back-breaker -- a two-run triple from Bryson Stott. It was Díaz’s first career blown save in the playoffs.

“Díaz, he’s one of the best closers in the game for a reason, and his stuff is electric,” Stott said. “His fastball was running more than it has, it felt like, in the past. I was trying to beat one of those heaters to the outside part of the plate. He threw a slider that I thought I could finally hit, and was able to pull it down the line.”

Still the Mets fought back, tying the game in the top of the ninth on Mark Vientos’ second two-run homer of the day. They just couldn’t push across the winning run. The Phillies eventually did, when Megill walked two batters with two outs in the ninth and Castellanos ripped a single into left.

“I did like that pitch when I saw it,” Castellanos said.

While Megill may not have been the Mets’ top choice in that spot, Mendoza only had so many options given the circumstances of the past week. Simply to clinch a spot in the NLDS, the Mets had to play eight games in seven days, including a crucial doubleheader in Atlanta and an elimination game in Milwaukee. Given all that, Mendoza has pushed Díaz and top setup men Phil Maton and Ryne Stanek far harder than he ever did during the regular season.

Last Sunday and Monday, for example, Díaz threw 66 pitches, his highest total over any two-day stretch of his career. He’s thrown 130 pitches in total over the last eight days. Maton, meanwhile, appeared in three consecutive games at the end of the season. Stanek pitched in three of the Mets’ first four playoff games. Both setup men were unavailable for NLDS Game 2.

To fill in the gaps, the Mets have pressed two of their regular starters, David Peterson and Megill, into bullpen duty, in hopes that their stuff might “tick up,” as pitching coach Jeremy Hefner put it, in shorter spurts. It’s a strategy that had largely worked -- until Sunday.

“It’s a challenge, but guys will step up,” Mendoza said. “You’re trying to stay away from different guys, because you’re going to need all of them.”

“It’s all hands on deck,” added Nimmo. “You’re trying to piece it together however you possibly can to win the game.”

Despite being unable to do so, the Mets could at least take several bits of consolation with them on their bus ride up the Jersey Turnpike. One was the performance of Vientos, who continues to prove he’s ready for the brightest lights this sport has to offer. Another was the play of Nimmo and Pete Alonso, who both homered.

But the most important might be the fact that the Mets have an off-day on Monday -- a chance for Díaz, Maton, Stanek and every other reliever to rest.

“This is a big moment for us,” was how Díaz put it, “and I’ve got to be ready always.”