NEW YORK -- Hours before the Mets’ series finale against the Braves on Sunday, a conference convened in the home batting cage. Brandon Nimmo was there, along with manager Carlos Mendoza, head trainer Joe Golia and two hitting coaches. The subject: Nimmo’s tight right intercostal.

About 24 hours earlier, Nimmo had tweaked his intercostal -- a small but crucial midsection muscle -- in a loss to the Braves. Mendoza’s initial instinct was to shut Nimmo down completely, and he told his starting left fielder as much. Nimmo understood. But when he arrived at Citi Field on Sunday feeling only a dull soreness in his right side, Nimmo began trying to convince his manager to change his mind.

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“Come watch me hit in the cage,” Nimmo implored.

So Mendoza did. When the group began challenging Nimmo with high-velocity offerings from a pitching machine, his swing looked normal. His midsection wasn’t barking. Performance testing came back well enough for everyone to agree that Nimmo was fit enough to play.

What they couldn’t have envisioned was the impact Nimmo would ultimately make, hitting a walk-off, two-run homer in the ninth inning to lift the Mets to a 4-3 win over the Braves.

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“For him to go through what he went to yesterday and today, just to be available kind of shows the player that he is,” teammate Jeff McNeil said.

From the time he exited Saturday’s game until the time he entered Sunday’s as a pinch-runner in the bottom of the seventh, Nimmo did everything in his power to heal his midsection quickly. Intercostal strains can be tricky injuries, often requiring 6-8 weeks or more to heal. Nimmo’s fear -- one underscored by the opinions of both Mendoza and Golia -- was that trying to do too much, too soon would be a grave mistake. Given that it’s only mid-May, the gamble hardly seemed worth it.

But as Nimmo said on Saturday night, “24 hours in baseball is a lot.” He spent that time icing his midsection and utilizing some of the treatment modalities the Mets have available in their clubhouse, including laser therapy, heat therapy and electrical stimulation. Golia and other trainers poked and prodded him. By Sunday afternoon, Nimmo felt strong enough to begin politicking.

“I wanted to see it myself,” Mendoza said. “I was like, ‘Really? He’s feeling that good?’ But once I saw it, it was pretty clear that he was ready to go today.”

By game time, all parties involved had signed off on the decision. In the eyes of Mets trainers, it was no longer a gamble; using Nimmo did not constitute a medical risk. Mendoza was plenty willing to do it, albeit only if game circumstances warranted doing so.

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Pete Alonso made those circumstances happen with game-tying hits in the third and sixth innings, taking Luis Severino off the hook for a loss on each occasion. Hoping to take the lead for the first time in the seventh, Mendoza called on Nimmo as a pinch-runner. Although he didn’t wind up scoring, Nimmo impacted the game half an inning later with a leaping, twisting catch to rob Matt Olson of extra bases on the warning track. As he hit the ground, Nimmo collided lightly with the outfield fence.

“That was a great first test,” Nimmo said. “Hey, get it out of the way right away.”

The Braves ultimately took the lead anyway, but McNeil sparked a ninth-inning rally with a drag bunt against left-hander A.J. Minter. Tomás Nido followed with a sacrifice to bring up Nimmo, who ran the count full before crushing a 90-mph cutter over the right-center-field fence.

“Pure adrenaline,” was how he described the feeling of rounding the bases with a wide grin on his face, fists pumping at various points along the route. As Nimmo jumped across home plate, Francisco Lindor met him in midair, throwing his arm around the outfielder and dragging him into a pile of other teammates.

His intercostal survived that interaction, too.

“If we weren’t sure enough that we were OK, we are now, because Francisco just about sucked the air out of me when he hugged me,” Nimmo said, laughing. “It was a beautiful thing, and I would do it all over again.”