NEW YORK -- One start into what he hoped would be a breakout campaign, Tylor Megill is on the injured list.

The Mets placed Megill there Monday, a day after he exited his debut start against the Brewers due to shoulder discomfort. A subsequent MRI revealed a strain, prompting New York to shut Megill down for a period of five to seven days. He’ll restart a throwing program after that with no clear return timeline.

Megill missed three months due to a similar injury in 2022, but the right-hander says this shoulder strain is “nowhere near” as bad.

“Just a little bit of soreness, typical soreness after throwing,” Megill said. “The pain isn’t anything significant, so that’s positive. … It just hit me out of nowhere. Been feeling good, feeling great, then just threw one pitch and all of the sudden feel a little pull, tightness. It sucks.”

Complicating matters is the fact that the Mets initially won’t be able to use their top Minor League rotation option, José Buttó, in Megill’s place. Because the Mets optioned Buttó to Triple-A Syracuse before the season, Buttó isn’t eligible to be recalled until April 12. That rule carries an exception clause if the team simultaneously places a player on the injured list. With six days until Megill’s next scheduled start and plenty of rain in the forecast, Mets officials took a different tack, recalling reliever Reed Garrett instead.

The Mets next need a fifth starter on Saturday. They don’t have any obvious non-roster candidates at Syracuse, unless they’re willing to call up a prospect such as Christian Scott (Mets No. 5 prospect) or Mike Vasil (No. 11). More likely, the team will proceed with a bullpen game or find a spot starter from outside the organization.

To that end, a source confirmed that the team is considering outside options, as SNY first reported in linking the Mets with Julio Teheran. Like several veterans on Minor League deals, Teheran opted out to become a free agent near the end of Spring Training. But the cumbersome mechanics of signing someone effectively for a spot start could sway the Mets, who can turn to Buttó later in April if they desire.

Most likely, team officials will take a beat before making a decision, particularly with rain threatening to postpone one or more games this week.

If Buttó does eventually join the team, it could hurt Megill’s chances to become a permanent rotation member -- a chance he earned after pitching well in the absence of Kodai Senga, who will be sidelined at least another month because of a shoulder strain of his own. Megill, who made a career-high 25 starts last season, will need to reestablish himself as a rotation option once he returns. But by that time, other factors -- Buttó, Senga, perhaps an outside arm -- could complicate the situation.

“I’m obviously not happy about it,” Megill said. “I’ve felt good this whole offseason, felt good all spring, then just happens to happen in my first start back. Obviously, I wasn’t looking for that to happen. It just sucks. But I can only do what I can do right now, give it a little rest and then start building up.”