ST. LOUIS — One day after the highly anticipated pitchers’ duel devolved into a pyrotechnics display, the principals crossed paths in the outfield grass. They shared a moment, bemused by the game’s enduring ability to throw curveballs.

Nobody had seen it coming, particularly the Giants’ Madison Bumgarner and the Mets’ Jacob deGrom.

“Those are definitely frustrating,” deGrom said a few days later, the dust long settled. “I actually talked to Bumgarner about it. Neither one of us had planned on that game going like that.”

But for deGrom, pressing matters have left little time to dwell about one of the worst starts of his career. The Mets righthander takes the mound Wednesday night against the Cardinals, with his team’s slim playoff hopes hanging in the balance. There is no room for mental clutter.

“I’m ready to get back out there,” deGrom said. “When you have those like that, you’re ready to get back on the mound and get things back where they need to be.”

There is no margin for error. The Mets have left themselves none. Beaten down by injuries, and regression by the likes of Michael Conforto and Travis d’Arnaud, the Mets’ playoff hopes are flickering.

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Entering play Tuesday, the Mets stood at 62-62. FanGraphs gave them just a 13-percent chance of qualifying for the postseason. The Mets’ vaunted rotation has been hit so hard that the unproven Seth Lugo and the struggling Jonathon Niese have become fixtures.

The problem with such dependence reared its ugly head Tuesday, when Niese left the game with an apparent knee injury after facing only four batters. It’s even more motivation for the Mets to make the most out of starts by Bartolo Colon, Noah Syndergaard and, of course, deGrom.

“Right now, we’re leaning on those three guys that we started out the year with,” manager Terry Collins said. “They are the guys that certainly when they go out there they’ve got to give us maximum innings.”

Again, deGrom (7-6, 2.73 ERA) faces extra pressure to pitch deep into his start, especially with the bullpen taxed after Niese’s outing. The Mets can’t afford a repeat of the horrors in San Francisco.

“You have those days,” deGrom said. “Good pitchers have bad outings. That’s part of it. Yeah, you’re frustrated about it. But you’ve got to go out there and get ready for this next one.”

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In the Mets’ 10-7 loss to the Giants on Thursday, Bumgarner and deGrom combined to allow 12 runs and 19 hits. But the brunt of the damage belonged to deGrom, who set career highs in hits (13) and runs (8). And it was his counterpart who added the twist of the knife, bashing a fourth-inning homer.

It was a rare step backward for deGrom, who pitched well despite velocity that did not round into form until much later in the summer.

“He stayed with it, the program, he stayed with pitching and he got himself on track,” Collins said. “It was huge.”

But against the Giants, not only had they knocked deGrom around the yard, they did so with hard contact that pointed at faulty location.

“Again, velocity was very good,” manager Terry Collins said. “Pitching, the location, was just off. It was just one of those nights that every time he made a bad pitch, they centered it. But he’s been pitching so well, you’ve just got to shrug it off.”

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And that’s precisely where deGrom turned his attention, even before coming across Bumgarner in the outfield during batting practice.

“It’s over with,” deGrom said. “There’s nothing I can do now. Once the ball leaves your hand, it’s out of your control. A lot of those go down the middle and got hit hard. It’s part of the game. You make mistakes. It’s big-league hitting.”