PHILADELPHIA — The Mets did not have a true starting pitcher and did not want to use their closer.

It did not matter on a night when creativity beat tradition.

The Kodai Senga experiment was short-lived, giving way to a hybrid bullpen game that gave the offense a chance — a chance it would run with in the eighth inning.

After Senga pitched just two frames, the Mets bullpen stitched together seven one-run innings with four pitchers — a group that did not include Edwin Diaz — to steal a 6-2 win in Game 1 of the NLDS over the Phillies at Citizens Bank Park on Saturday.

Zack Wheeler was filthy, but David Peterson, Reed Garrett, Phil Maton and Ryne Stanek, who followed Senga, did not blink.

“Everyone that we needed was ready to go,” said Peterson, who was the first fireman.

The lefty was a starter who was bounced out of the playoff rotation by Senga after posting a 2.90 ERA in 21 starts.

He handled the October demotion with grace and excellence.

Peterson, who recorded the save in Game 3 in Milwaukee, knew he would be used early Saturday but did not know the inning.

It turned out to be the third, an inning that typified his outing: Two Phillies reached base, but an in-trouble Peterson induced a fly out from Nick Castellanos to escape.

Peterson continually pitched out of danger during an outing in which he walked three.

“He did a tremendous job,” manager Carlos Mendoza said of Peterson. “Reed Garrett, and then Maton and Stanek. … Overall, a good team win there.”

Garrett was dominant for two perfect frames. He faced the Nos. 4-9 Phillies hitters and was not touched.

After his scoreless seventh, he watched the Mets offense come alive in the eighth, which helped the 31-year-old Garrett earn his first career win in the postseason.

“I asked for the lineup card — it means a lot,” said a smiling Garrett, who will frame the card and add it to his mementos at home.

Maton, pitching for a fifth time in eight days, got into trouble in the bottom of the eighth, when he allowed a pair of hits.

But just like a Mets offense that seems to thrive in the clutch these days, Maton stranded the runners with an Alec Bohm ground ball that Jose Iglesias, shifted over to third base, handled well.

After Diaz threw 39 pitches Thursday — making it 105 pitches since Sunday, a workload he had never seen before — he did not warm up until Stanek allowed a ninth-inning run.

But with a runner on second, Stanek bounced back to retire Kyle Schwarber to finish off an inventive and effective pitching night.

“Resilient. I feel like that just kind of sums up who we are,” Garrett said. “You put us in a corner, we’re going to fight our way out of it.”