A quiet Opening Day at Citi Field took a loud and ugly turn in the top of the eighth inning.

The Mets and Brewers’ dugouts and bullpens emptied and shouts — but no punches — were exchanged after a hard slide from Rhys Hoskins took out Jeff McNeil at second base on Friday.

Hoskins slid late — but within the rules — to attempt to break up a double play on a ground ball from Willy Adames in a game the Brewers led 3-1.

McNeil caught the throw with his foot on the base and tried to complete the turn but was upended and clearly angry.

McNeil got to his feet and stood above Hoskins, shouting at him even as Hoskins got up and began running off the field.

Hoskins turned around near third base and shouted back, at one point balling his fists and putting them by his eyes in a “crybaby” gesture.

After a few minutes, players from both teams returned to their sides and the Mets challenged — unsuccessfully — for a violation on Hoskins, who was able to hang on to second base and did not sail past it.