Noah Syndergaard and Yoenis Cespedes have been the pillars that have propped up the Mets, even as they have been beset by injuries. But both fell victim to the wave Friday night, exiting the Mets’ 3-1 loss to the Nationals with new maladies of their own.

On a day in which the Mets announced season-ending surgery for Matt Harvey, Syndergaard departed with what he insisted was arm fatigue that is unrelated to his elbow. Cespedes was pulled with a strained right quadriceps.

Syndergaard reported “no concern from the doctors” after being checked out following his 4 2⁄3-inning stint and suggested that his fatigue is simply a product of pitching in his first full season in the majors.

After leaving in the fourth, Cespedes said a similar injury earlier in his career sidelined him for four to five days.

“I’m running out of things to say and we’re running out of bodies,” said Terry Collins, whose news conferences have become daily medical briefings.

Syndergaard and Cespedes were to play in Tuesday’s All-Star Game, but Collins said it’s virtually assured that neither will participate in the festivities. “It’s part of destiny,” Cespedes said of potentially missing the game. “I have no control over it.”

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Said Syndergaard: “It’s disappointing, but hopefully there will be a lot more.”

Syndergaard’s last three fastballs were clocked at 93, 93 and 91 mph, well off his season average of 98 mph. He has been pitching through a small bone spur in his elbow. Twice this season, he has had his elbow checked out as a precaution, though he denied any connection.

On Syndergaard’s 79th pitch of the night, he missed up and in with a 91-mph fastball. Catcher Rene Rivera jogged to the mound. From the dugout, Collins didn’t like what he saw and summoned trainer Brian Chicklo. “He just said his arm went dead,” Collins said.

Syndergaard was pulled with the Mets down 3-0, having allowed three runs and four hits. He struck out five but issued three walks, all as his fastball lost its steam. He maintained that he felt no pain. “Really, it all boils down to a little shoulder fatigue,” Syndergaard said.

Cespedes appeared to move awkwardly as he pursued Daniel Murphy’s double to the left-centerfield gap in the third. He began the day hitting .303 with 21 homers and 52 RBIs, was tied for fourth in the NL in homers and was second in slugging (.585).

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With Harvey’s struggles, Syndergaard has emerged as the staff ace. He entered his start 9-3 with a 2.41 ERA, the fifth-best mark in the big leagues. His 8.20 strikeout-to-walk ratio was second in the majors.

Now both face uncertainty, the latest jolt to a Mets team that has been besieged. David Wright is out for the year after surgery to remove a herniated disc. Lucas Duda still is in the middle of a lengthy rehab for a stress fracture in his back.

Steven Matz is pitching through a large bone spur in his left elbow, one that has forced the Mets to evaluate him start by start. The pain could prompt season-ending surgery at any time. Harvey, of course, has been lost for the season.

Zack Wheeler was expected to provide a boost for the Mets, with the end of his rehab from Tommy John surgery coinciding with the start of the season’s second half. But after enduring two setbacks, the Mets have avoided providing a timeline for Wheeler’s return.

The game itself brought no respite. Asdrubal Cabrera homered for the Mets’ only run against Stephen Strasburg (12-0), who went seven innings.