For nearly nine innings, the Mets had come out on Father’s Day and put on a Little League display. They couldn’t field, couldn’t hit, couldn’t compete. Then Kirk Nieuwenhuis turned all that around, the same way he turned around Carlos Marmol’s fastball for a walk-off blast and a 4-3 come-from-behind win.

Nieuwenhuis crushed Marmol’s 1-0 pitch out to right field in the bottom of the ninth inning for a three-run blast, plating Lucas Duda and John Buck and salvaging what seemed destined for another crushing error-filled loss to the Cubs in front of a stunned Citi Field crowd of 30,256.

As Marmol smashed things in the Cubs dugout, the Mets formed a mob at home plate and celebrated. And why not? They had clearly earned something to be happy about for a change.

Bobby Parnell got the win and Marmol the loss, in a shocking turn of events.

The Mets had made three overthrows and two errors on the same fifth-inning play, letting two runs score and throwing away the game in the process. Starter Jeremy Hefner, who allowed six hits and three runs – just one earned –in his five innings wasn’t terrible Sunday, but almost took the loss.

After a shaky start, allowing three hits and Alfonso Soriano’s RBI single in the first, Hefner settled in nicely and trailed just 1-0 into the fifth.

Hefner retired counterpart Matt Garza and Luis Valbuena, only to surrender a single to Starlin Castro and walk to Nate Schierholtz. He induced a ground ball from Soriano, but David Wright airmailed his high throw to first over Daniel Murphy’s head to send Castro to third and Schierholtz to second.