ATLANTA — As the celebratory Mets jogged off the field following their dramatic, 8-7 win over the Braves in the doubleheader opener Monday, they had a welcoming party in the dugout.

On the top step, awaiting with words and handshakes, was a smiling Steve Cohen.

The owner had moved from his seat 11 rows behind home plate after seeing his club crack into the postseason on the strength of a top-of-the-eighth rally, a collapse in the bottom of the inning and a two-run home run from Francisco Lindor in the ninth.

“I’ve never seen a game like that,” Cohen said after the Mets split the pair of games. “They never quit. I’ve never seen a more resilient group. They believe in themselves, and a lot of people didn’t.”

Cohen was part of his first playoff-clinching party, drenched like his team and doused at one point by Brandon Nimmo.

In Year 4 as owner, Cohen watched his team dig an 11-games-under-.500 hole in early June and emerge as just about the best team in baseball since.

They needed one more victory to assure a wild-card spot, and they aptly got it in dramatic, come-from-behind fashion.

“I was in tears in the eighth inning when we went ahead,” Cohen said on the field at the end of the night. “I was in shock when we lost the lead. And then Francisco stepping up — an incredible moment.”

He credited a group that always believed.

He credited first-year team president David Stearns, who has remade the team on the fly.

“When you think about the roster at the beginning of the season versus where we are now, totally different roster,” Cohen said. “That just shows the tenaciousness.”

He credited first-year manager Carlos Mendoza, one of the “most optimistic, positive” people around.

And he was ready for Milwaukee.

“It’s an amazing feeling,” Cohen said. “I can’t believe what these guys pulled off.”

— Additional reporting by Joel Sherman and Mike Puma