Mets ace Max Scherzer is dealing with a hamstring issue and isn’t sure when he’ll pitch next, another frustrating setback for the top of New York’s heralded but suddenly fragile rotation.

A day after the Mets said star Jacob deGrom will miss significant time with a shoulder injury, Scherzer was scratched from his outing Saturday morning in a simulated game.

Just five days away from opening day in Washington, Scherzer said he wasn’t sure about the immediate plans. The three-time Cy Young Award winner said he doesn’t expect the trouble with his right hamstring to be a long-term problem.

“Don’t know,” Scherzer said when asked when he’d pitch again. “I’ve had these little hamstring injuries before. They go away in days. Fortunately enough I’ve been pretty good to not have serious hamstring injuries. I’ve had just little hiccups.”

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

Mets manager Buck Showalter said he would lean on the 37-year-old right-hander for advice going forward, but added that Scherzer was still in consideration for the opening day nod against his former Nationals teammates.

“If you look at the days and off and what have you, yeah, but I’m not committed to that,” Showalter said.

The Mets signed Scherzer as a free agent to a $130 million, three-year contract. That seemed to give them a dominant front of the rotation, but the news that deGrom wouldn’t throw for up to four weeks but a huge dent in those hopes.

There is no timetable for deGrom’s return. In addition to the time he won’t throw, the two-time Cy Young Award winner might need at least a month after that to get ready to pitch in the majors — and that might be a best-case scenario after he missed the second half last year because of an elbow injury.

All-Star Chris Bassitt, acquired last month in a trade with Oakland, is set to pitch Sunday’s Grapefruit League contest. Carlos Carrasco and Taijuan Walker are lined up to round out the rotation’s back end.

“Just because something doesn’t happen on the first game of the season, I’m not going to put the whole thing in disarray for one spot or even two spots,” Showalter said.

“We have options to go in different directions if we want to. I told all three of those guys to continue down the path you’re on right now,” he said.

Two other pitchers might be of service to keep the rotation in order.

Right-hander Tylor Megill and southpaw David Peterson — the first two starters outside of the predicted starting five — have both been stretched out to five innings this spring.

“They’ve presented themselves as physical options, for sure,” Showalter added.

Thursday proved to be the source of Scherzer’s ailment.

“I’d noticed something a couple days ago from running,” he said. “Hamstring just tightened up, didn’t feel like I strained it or anything like that. I had good recovery the past two days.”

“Then I went through my normal routine to go for it and make a start today, and the hamstring just tightened up,” he said.

Unlike deGrom, Scherzer said he would still be able to maintain part of his routine, making his recovery less time-consuming than deGrom’s.

“Fortunate enough this doesn’t really affect when I throw, so I’m able to get into my throwing mechanics,” Scherzer said.

The American League Cy Young winner in 2013 for Detroit before capturing a pair with the Nationals in 2016 and 2017, Scherzer said had a great offseason workout routine. The start of spring training was delayed this year as Major League Baseball owners and players worked to settle a 99-day lockout.

“It’s frustrating. I’ve really worked hard this offseason — lifting my legs heavy, doing all the running. I feel like I was in a really good spot with my body and my arm,” Scherzer said.