A teenager was stabbed in the arm during a fight in Washington Square Park early Sunday morning, cops said.

The 18-year-old was knifed by a man he didn’t know around 12:30 a.m. after a fight started inside the iconic lower Manhattan park, cops said. Police sources said he was stabbed from behind.

The victim, who was uncooperative, was expected to survive, cops said. He traveled to Beth Israel Medical Center on his own for treatment.

The park had been the location of celebrations after Joe Biden declared victory in the Tuesday presidential election, but it was unclear if the teen was participating in the revelry, cops said.