And then there was one.

Noah Syndergaard has stood by and watched as every other young Mets starting pitcher experienced setback after setback this year. There was Matt Harvey, done for the season, and Steven Matz, with elbow and shoulder problems. Zack Wheeler never even made it to the major-league roster after undergoing Tommy John surgery in March 2015. And now this: Jacob deGrom, who is experiencing soreness in his right forearm, more than likely will miss his next start.

But despite a few hiccups, Syndergaard — the hardest thrower of the bunch and yet the only one to never have had Tommy John surgery — has soldiered on. But even he can’t do it alone.

Syndergaard pitched well enough to win in Friday night’s 4-1 loss to the Nationals at Citi Field, but the Mets’ bats wilted against A.J. Cole, who was making his fourth major-league start. The Giants and Cardinals also lost, meaning Friday night was yet another squandered opportunity to inch forward in the race for the second wild-card spot. The Mets trail the Cardinals by two games.

Syndergaard (12-8) and Bartolo Colon are the only original starters left standing, and before the season, everyone believed Colon would be working out of the bullpen by now.

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“It’s just really unfortunate to hear about it,” Syndergaard said of deGrom. “He’s an awesome competitor and an even better friend of mine, and it’s really unfortunate to hear the news about him. You just got to go out there and keep things simple.”

Syndergaard allowed two runs, three hits and a walk in seven innings, retiring the last 10 to face him. But in a similar old song, stolen bases hurt him.

Trea Turner led off the game with a single and proceeded on an easy jaunt to second and third, with neither throw by Rene Rivera close to preventing a pair of steals. He scored on Bryce Harper’s sacrifice fly. Daniel Murphy walked and stole second, but that was for naught as Syndergaard got Anthony Rendon to fly out to left.

Syndergaard mowed through the lineup in the second and third, but it was more of the same in the fourth. Harper doubled with one out, stole third and scored on Wilson Ramos’ two-out single for a 2-0 lead.

Syndergaard leads the league with 45 stolen bases allowed, according to FanGraphs. The next-highest total for a pitcher belongs to the Brewers’ Jimmy Miller, who has allowed 26.

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The Mets sliced their deficit in half in the fourth, thanks to the hot Asdrubal Cabrera.

He blasted an 0-and-2 two-seamer about 400 feet — but about 10 feet foul. With the way he’s going, though, all he needed was another shot. The next pitch, a 91-mph two-seamer, went about 370 feet to right-center, good for his sixth homer in eight games and his 19th of the year.

The Nationals tacked on two runs in the ninth on Rendon’s single off Hansel Robles. It drove in Murphy and Harper, both inherited runners from Jerry Blevins.

Still, give Terry Collins and the Mets credit for not panicking. Syndergaard, who fought through a bone spur and an inconsistent stretch in late July and early August, has had four straight strong starts, and the team believes deGrom’s prognosis is good news. And remember, before losing these last two, the Mets won nine of 11, injuries and all.

“It’s all about us taking care of our business,” Collins said. “If we go out and play like we did the last 10 days the next 10 days, we’ll be OK.”