NEW YORK » Chris Young hit a tiebreaking homer in the eighth inning, Jenrry Mejia provided a jolt after his reluctant move to the bullpen and the previously punchless New York Mets went deep four times to rally past the Yankees 9-7 Monday night in the Subway Series opener.

Curtis Granderson connected in his return to Yankee Stadium, and the Mets also got long balls from Eric Young Jr. and Travis d’Arnaud while overcoming a pair of three-run deficits.

Lumbering first baseman Lucas Duda turned in two spectacular defensive plays, starting a game-ending double play with runners at the corners by making a diving stop of Brian McCann’s sharp grounder.

Taking full advantage of the hitter-friendly confines across town, rather than the vast dimensions back home at Citi Field, the Mets hit four home runs in a game for the first time since May 3, 2013, in Atlanta, according to STATS. They began the day ranked 29th in the majors with 22 home runs.

Brett Gardner hit an early grand slam off ex-Yankee Bartolo Colon, and Derek Jeter had three hits for the first time since September 30, 2012, in Toronto.

Bumped to the bullpen before the game, Mejia (4-0) entered in the seventh for his first big league relief appearance since September 2012. He struck out Alfonso Soriano on three pitches and worked a scoreless eighth.

Mejia sure seemed to relish the role — even though he made it clear he wanted to stay in the rotation because he was concerned about injuring his surgically repaired arm again. The right-hander excitedly pumped his fist after a double play and then backed his way off the mound following a called third strike that ended the eighth.