Mets 3, Pirates 2: Mike Baxter singled home Marlon Byrd in the bottom of the ninth as host New York won the opener of a four-game series.

Baxter’s pinch-hit single to center with one out off Pittsburgh closer Jason Grilli (0-1) gave the Mets their fourth victory in the past 12 games. Bobby Parnell (4-0) picked up the victory with a scoreless ninth inning.

Pedro Alvarez drove in both Pittsburgh runs on a sixth-inning sacrifice fly and a game-tying solo homer leading off the eighth. The Pirates have lost six of their past nine.

Byrd opened the ninth by reaching on an infield single. After Andrew Brown’s bunt moved Byrd to second, Baxter hit for Juan Lagares and delivered the game-winner.

New York snapped a 1-1 tie in the seventh on Ike Davis’ RBI double to right center, scoring Brown. Alvarez connected off LaTroy Hawkins to tie the contest at 2.

GAME NOTEBOOK: Pittsburgh starter Jeff Locke allowed one run on three hits in six innings. … New York starter Dillon Gee scattered five hits across five innings, allowing one run. … New York plays 13 of its next 20 games at Citi Field.