PHILADELPHIA — One day Kodai Senga is pitching in Florida, wondering whether he’s wasting his time trying to get healthy for a game that may not exist.

The next, Pete Alonso is hitting a game-winning three-run homer in Milwaukee, keeping the New York Mets’ Cinderella season alive, and Senga is boarding a plane to join his teammates in Philadelphia for one the most improbable starts in Major League Baseball postseason history.

Senga, who has pitched just once all season, lasting a grand total of 5⅓ innings on July 26, is starting Saturday afternoon against the powerful Phillies in Game 1 of the National League Division Series.

Yes, really.

The stunning announcement resurrects memories of 2016 when Chicago Cubs outfielder Kyle Schwarber missed their entire regular season recovering from knee surgery, only to return in time for the World Series as a designated hitter.

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So how long can he possibly go in the first postseason game between these two NL East rivals?

“I'm ready for whatever," Senga said. “If they say 10 pitches, I'm all in for 10 pitches. If they say 200, I'm in for 200."

Uh, when did you ever throw 200 pitches?

“Five years ago," Senga said without cracking a smile – as nobody stresses over pitch counts in Japan.

Mets manager Carlos Mendoza played it coy when asked, saying he also has no idea how long Senga will pitch.

"We'll see, we're going to let it play out,’ Mendoza said. “We have a plan. But we're going to go out there and watch him closely, and go from there."

Ultimately, it may be up to Senga.

He was the one who informed the Mets that he finally felt good enough to join the club after missing the first four months with a strained right shoulder, and then the last two months with a calf injury.

If he feels fine, and pain free, he could be pitching until he tells Mendoza it’s time to stop.

“If anybody knows himself better than anybody, it's Kodai Senga," Mendoza said. “We've been through it a whole year with him. And the times that he goes out there and faces hitters or throws a lot of bullpens and he's not feeling right, he's always letting us know that. And that wasn't the case in this situation. He was the one that approached us and he wanted to know what we were thinking in case, you know, we were here in the Division Series or potential NLCS.

“We just wanted to hear what he had to say ... He's excited. He said right away when we talked to him that he was ready to go."

This is a guy who has frustrated the Mets all season, patiently waiting for him to be ready, and once he was, pitched into the sixth inning against Atlanta, struck out nine hitters, and then limped off the field.

He spent the rest of the summer rehabbing, and was last seen throwing a bullpen session against Mets’ minor leaugers on Monday at their Port St. Lucie, Fla., complex.

He knew the Mets were waiting on him, and finally told the team Wednesday it could count on him if they make the next round of the playoffs.

Alonso then hit the homer heard 'round New York, the Mets were moving on, and Senga was boarding a plane.

“I think it's simply that they've been very transparent with me," Senga said, " 'Whenever you're ready we would love to use you.’ And I was able to get my physical and mental state up and ready to this point and they were able to plug me in. …

“I feel physically ready. It's a feel thing. But I feel ready now."

The Mets didn’t even know that they’d even be in the postseason until beating Atlanta in the first game of a makeup doubleheader Monday. They survived a grueling best-of-three series against the Milwaukee Brewers with Alonso’s ninth-inning magic, certainly could use Senga to bolster their fatigued rotation.

But Senga’s teammates would be lying to you if they believed Senga was ever an honest-to-goodness option, with some players having already given up on the idea.

“I was surprised," said Mets starter David Peterson, who played an integral role in Senga’s absence, going 10-3 with a 2.90 ERA. "We hadn't really talked about it much. I think everybody is glad to have him back, especially kind of the way the first time around this season went with him and only having him for the one start.

“So, it's exciting to have him, another elite arm that we have at our disposal, and excited to watch him compete."

Still, you’re talking about a pitcher who will have thrown less than six innings in the last 374 days when he takes the mound at Citizens Bank Park in front of a frenzied sellout crowd.

“I think just coming back into an atmosphere like that, getting back up to game speed,’’ Peterson said, “is something that's going to be a challenge when you're coming back like that. But I have no doubt [with] the work he's put in, and the way he's gotten himself prepared, he's ready for the challenge."

The Mets say they truly have no idea what to expect, but considering he dominated a powerful Atlanta lineup when he finally made his season debut in July, maybe history will repeat itself on the biggest stage of his MLB career.

“This is no joke right here when he's facing the Phillies, Game 1 of the Division Series,’’ Mendoza said. “But, again, not watching him the whole year and then going out and facing that Braves lineup was pretty impressive. We'll see how he goes, and again, we'll be ready to adjust if we need to.""

Certainly, Senga knows the Mets have full confidence in him. If they didn’t think he was ready, or could last just an inning or two, they wouldn’t have him wasting a valuable spot on the pitching staff. You wouldn't remove a pitcher from your roster for the Division Series if you have serious doubts about Senga’s ability to provide innings.

“The team believes in me," Senga said, “and I believe in myself. All I can do is go out and perform. …I'm looking forward to it."

It worked out quite nicely for Schwarber and the Cubs in 2016, winning their first World Series in 108 years.

The way the Mets are pulling off miracles with their dramatics, hey, why not another?

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