As reported on Friday, Jacob deGrom has been shut down from throwing for up to four weeks after an MRI exam revealed a stress reaction on his right scapula.

The two-time Cy Young Award winner will have to build up his arm strength again once he resumes throwing. This could push his eventual return to the rotation sometime around late May or early June.

Despite the uncertainty of his injury or a timeline for his return, deGrom says he still plans to opt out of his contract at the conclusion of this season.

Last season, back and forearm issues limited deGrom to only 15 starts, and he last pitched on July 7. Other than a mild case of rotator cuff tendinitis in 2014, deGrom has never had any shoulder problems in his career.

Adding to the Mets’ uncertainty regarding the top of their rotation, right-hander Max Scherzer is dealing with a hamstring issue and isn’t sure when exactly he will pitch in a game again.

Scherzer, 37, was scratched from his outing on Saturday morning, and the team says he is expected to pitch in a bullpen session on Tuesday.

“I’ve had these little hamstring injuries before,” Scherzer told reporters. “They go away in days. Fortunately enough I’ve been pretty good to not have serious hamstring injuries. I’ve had just little hiccups.”

“For me, it’s just a day-to-day thing … but when you’re dealing with hammies, you never know.”

With Opening Day only four days away, young right-hander Tylor Megill told reporters he would be ready to pitch if needed.

Megill, 25, impressed at times during his rookie season. He posted a 4.52 ERA and 1.28 WHIP over 18 starts while striking out 99 in 89 2/3 innings. However, he also allowed 19 home runs.

All in all, what was supposed to be one of the league’s most vaunted top of the rotation, has suddenly revealed just how fragile it is.