Mets pitcher Kodai Senga speaks during a press conference Thursday...

Mets pitcher Kodai Senga speaks during a press conference Thursday in Port St. Lucie, Fla. Credit: Newsday/Alejandra Villa Loarca

PORT ST. LUCIE, Fla. — It will be a while before the Mets get Kodai Senga back.

The righthander is likely to miss at least April after receiving an injection on Friday for his strained right shoulder.

After the team shut him down last week, Senga went to New York to get a shot of platelet-rich plasma, Mets manager Carlos Mendoza said on Sunday. The injection is meant to accelerate healing.

Senga will not throw for three weeks, Mendoza added. Because of when he suffered the injury — early in spring training, before getting into any games — he essentially will have to restart his own personalized camp once he is cleared to do so. That typically lasts six weeks, sometimes longer for players returning from such a layoff.

“[The injection] was recommended by the doctors and Senga was on board with it,” Mendoza said. “Everything went well. But now it’s probably like three weeks of no throwing and letting the shot do the work before we can move forward with the plan.

“And once he starts ramping up his throwing program, we’ll have a better idea of how he’s bouncing back and all that. For now, we just have to let it heal.”

Mendoza characterized the first week and a half after the injection as “pretty much the key [to] the whole thing.”

“It’s really up to the condition of my shoulder,” Senga through an interpreter after returning to the Mets’ facility Sunday morning. “It’s day by day. Maybe it’s six weeks. I have no idea. So I really don’t have anything else to say right now.”

President of baseball operations David Stearns previously described Senga’s injury as a “moderate” strain of the right posterior capsule, which is in the back of his shoulder.

Platelet-rich plasma is produced from a person’s own blood and is a form of regenerative medicine, according to the Mets-affiliated Hospital for Special Surgery.

It basically supercharges the body’s ability to fix itself.

“[PRP] harnesses and amplifies the natural growth factors found in our blood cells to help heal damaged tissue,” HSS wrote on its website. “The activation of the concentrated platelets in platelet-rich plasma releases growth factors that stimulate and increase the number of reparative cells your body produces. This significantly enhances the body's natural healing process.”

Senga’s absence — and his being replaced by a backup starting pitcher — underscores the Mets’ longstanding desire for relievers who can pitch multiple innings, since the fill-in likely won’t pitch as deep as Senga could.

Mendoza mentioned Michael Tonkin, who served in that role for Atlanta last season, plus Sean Reid-Foley, Reed Garrett and Phil Bickford as bullpen arms who can do that. Grant Hartwig is another. The Mets have about two reliever spots up for grabs.

A man at the cross section of the Mets needing a starter and wanting multi-inning relievers pitched on Sunday: Jose Butto, who Mendoza mentioned as a bullpen option.

Butto tossed two scoreless innings against a lineup of Astros backups and minor-leaguers, working around three singles, striking out one and walking none.

He came away pleased with the pitches that were key to his success last September (3.29 ERA and 1.10 WHIP in five outings): a sharper slider and a sinker he learned from Hartwig.

The Mets have flirted with the idea of trying to use Butto as a reliever previously, but for now he is building up his arm strength as a starter. He is competing against Tylor Megill and Joey Lucchesi to claim Senga’s rotation spot. If he doesn’t win, maybe short work would work.

“Last year, I talked a lot with [pitching coach Jeremy] Hefner,” Butto said. “I said, if you put me in the bullpen [for] one inning, three innings, four — no matter what it is, I’m going to be ready. Just give me the ball. I’m going to be ready for any situation.

“All my career, I’ve been a starter. But we’ve got to make adjustments. I feel really good. I’ll be ready for any situation.”

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