The Mets named Kodai Senga the starting pitcher for Game 1 of the NLDS against the Philadelphia Phillies on Saturday.

PHILADELPHIA — In the next round of the playoffs, the Mets are starting with a surprise: Kodai Senga.

Senga will pitch Game 1 of their NL Division Series on Saturday afternoon against the Phillies, manager Carlos Mendoza revealed Friday, a sudden about-face after the Mets waited and waited for their best pitcher to want to get back on the mound while he didn’t quite feel ready.

Now, though, Senga has deemed himself fit to perform. He likely won’t pitch long — perhaps only a couple of innings — because of a series of injuries this season, but in the Mets’ view, something is better than nothing.

“It’s the power of the decision, right?” pitching coach Jeremy Hefner said on the field at Citizens Bank Park. “As much as we want him on the team and pitching for us, he has to decide. And he finally did that. He finally decided ‘I’m ready.’ So here he is.”

Senga, who appeared in only one July game in the entire regular season, said through interpreter Hiro Fujiwara: “They’ve been very transparent with me. ‘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.”

His return came together over the course of this week, according to those involved. Senga faced minor-league hitters in a live batting practice session Monday. By Wednesday, after he recovered normally, which was no sure thing, they discussed it more seriously: Could he be an option if the Mets advanced?

When they beat the Brewers on Thursday to finish their NL Wild Card Series, then met and spoke with Senga in person on Friday (after he had been working out in Florida), the Mets felt comfortable not only including him on the roster but giving him the ball in the opener.

 

“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,” Mendoza said. “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.

“And we just wanted to hear what he had to say and offer. And he was pretty honest with us, and it was an easier decision because of what we’ve been through with him the whole year.”

What they’ve been through built to some level of frustration by late September.

Senga initially got hurt in February, suffering a shoulder strain. He slowed his rehabilitation in May because his mechanics felt out of whack. Then he encountered triceps tightness and nerve inflammation.

When he finally returned on July 26, he tossed 5 1⁄3 innings against Atlanta but strained his left calf while getting out of the way of a pop-up.

He recovered from that, too, in time to make a brief rehab appearance with Triple-A Syracuse. He pitched one inning on Sept. 21, cutting the outing short because he again felt a triceps issue.

Team officials began shrugging when asked for an update on Senga. They didn’t know how he would feel or when. They were consistent in saying they wanted him back, but if he didn’t feel ready, there was little they could do about it.

Still, the Mets held out hope that maybe Senga would get there.

“What made us feel comfortable with this decision was that he was the one wanting the baseball,” Mendoza said.

The Mets’ announcement featured a degree of subterfuge, which is not uncommon in the majors, especially at this time of year. They are meeting the Phillies, a primary rival and the NL East champions, in the postseason for the first time.

Mendoza & Co. talked around how many pitches Senga, realistically, will be able to give them Saturday. Consider: In that minor-league game last month, he threw 15. On Monday at the Mets’ spring training complex, he threw 25, Mendoza said at the time. He changed the story Friday to “a lot.”

“I don’t really like speaking on that topic [of his live BP pitch count],” Senga said, smirking as Fujiwara conveyed his answer. “If you could think more ahead and ask questions concerning [Saturday], that would be great.”

How long would he be comfortable going against Philadelphia?

“If they say 10 pitches, I’m all in for 10 pitches,” he said. “If they say 200, I’m in for 200.”

With Senga limited, the Mets have starting pitchers David Peterson and Tylor Megill available in relief behind him, Mendoza said.

Think about it this way: For the Mets to win this series, they have to pitch at least 27 and up to 45 innings or more. Having Senga handle a few is better than the Mets’ other options, even if their other starters have performed well lately.

Is there risk involved?

“Oh, no, no,” Hefner said. “Even if he gives up runs or whatever, it’s still the right decision, because he’s really good. He’s shown he’s back to where he was before. Regardless of the outcome, the decision is good.”

The Mets like their chances. It’s another layer of fun — and chaos — in their whirlwind run. As Mendoza departed the podium, he wore a wide smile, satisfied with himself for dropping the big news.

“That,” he said, “was a lot of fun.”