It went from a party to a church gathering fast for the Mets on Friday night.

One moment, the largest crowd in two years at Citi Field was living it up, showering Jacob deGrom with chants of “MVP.” The next, the 26,637 fans in attendance were silent, holding their collective breath, wondering why the best pitcher in the sport was taken out after six dominant innings and just 80 pitches.

There was a reason for it. The Mets announced, during their 3-2 victory over the Padres, that deGrom has right flexor tendinitis, momentarily interrupting his magical season again.

After the game, however, deGrom said he wasn’t overly concerned. He knows what a serious elbow injury feels like — deGrom underwent Tommy John Surgery in 2010 and had another operation in 2016 to repair nerve damage in his elbow — and he said this wasn’t it. Ligament tests following his removal were clean. He said there’s a strong possibility he will make his next scheduled start, Wednesday.

“I’ve had a couple elbow issues before, and I know what that feeling is like, so my level of concern is not too high,” said deGrom, who went on the injured list for two weeks last month with tightness in his right side and back. “I’m pretty optimistic about it and pretty sure it’s gonna be something that we can treat and hopefully not miss any time.”

DeGrom said he felt something in his flexor tendon during the week, but never thought about missing the start. It felt better as the week went on, and it wasn’t until he was warming up in the sixth inning that it tightened up on him. After the frame, he told pitching coach Jeremy Hefner, who suggested it was best for him to call it a night and avoid making it worse. The Mets are planning to give deGrom extra treatment before his next start. An MRI exam isn’t expected at the moment.

“I’m pretty optimistic I’ll be out there in five days,” deGrom said.

Manager Luis Rojas echoed deGrom, saying that if his star pitcher isn’t overly concerned, he isn’t either.

“I’m trusting my pitcher,” Rojas said.

Losing deGrom would be a crippling blow for the first-place Mets, who already are without starting pitchers Carlos Carrasco and Noah Syndergaard for the foreseeable future. They added a depth starter on Friday by picking up Nick Tropeano off waivers from the Giants.

Even after deGrom’s premature exit, the Mets were still able to hold on, despite a two-run home run by the Padres’ Jake Cronenworth off Miguel Castro in the seventh inning. Seth Lugo, Aaron Loup and Edwin Diaz combined for the final eight outs as the Mets (31-24) improved to seven games over .500 for the first time this year.

When he was in the game, deGrom continued his sheer brilliance, both on the mound and at the plate. He struck out 10 over six shutout, one-hit innings and increased his batting average to an even .400 with a two-run single in the fifth. He lowered his ERA to 0.56, a record through 10 starts.

The Padres managed just one base-runner — Wil Myers on an opposite field single in the fifth inning — against deGrom, who reached double-digit strikeouts for the fifth time this year.

He retired the first 13 Padres he faced and struck out megastar Fernando Tatis Jr. twice. With his fourth inning strikeout of Tatis, deGrom reached 100 punchouts on the season in just 61 ²/₃ innings, the fastest ever for a pitcher since the mound was moved to its current distance of 60 feet, 6 inches in 1893.

DeGrom finally allowed a hit in the fifth, after striking out the side in the fourth. With one out, Myers sprayed a 3-2 slider over the middle of the plate into the hole between first and second base, ending the no-hit bid.

“Definitely the thought [of a no-hitter] creeped into my mind,” deGrom said.

The Mets broke through in the fifth inning. Kevin Pillar led off with a double and Billy McKinney doubled him home to break the ice. After Jose Peraza walked and Padres pitcher Blake Snell balked the runners to second and third, deGrom laced a 1-2 fastball in left-center field to make it 3-0. He now has more RBIs (five) than earned runs allowed (four).

“Jake’s from another planet, honestly,” said Diaz, who recorded four outs for his 11th save in 12 chances. “He’s on a different level and he might be the best player in baseball.”