Painful night at the ballpark for Lars Nootbaar … the St. Louis Cardinals star foul-tipped a ball so hard into his man region — he had to leave the game.

The incident happened in the fifth inning of the Red Birds’ Wednesday night tilt with the Oakland A’s … when Nootbaar was trying to send a changeup over the outfield wall.

Instead, however, his bat barely got a piece of the baseball as it crossed the dish … and it, unfortunately, bounced off the ground and ricocheted right into his junk.

At first, the game’s announcers believed it had smacked off one of his shins — but when the replays showed it went directly into his family jewels … they knew exactly what was going down.

Nootbaar, meanwhile, was in a world of pain … he writhed on the ground for several moments — before he somehow got up. He would go on to strike out during the at-bat … and then leave the game to get all checked out.

It’s unclear exactly how the guy is now doing … the Cards only said afterward he was removed “due to a lower abdomen contusion.”

To add insult to injury, Nootbaar’s Cardinals lost 8-0.