An unhinged stranger knifed a 51-year-old man in the back during an early Wednesday clash on the staircase of a Lower Manhattan subway station, cops and sources said.
The victim was standing on the steps at the Broadway-Lafayette hub around 5:20 a.m. when a maniac suddenly started arguing with him for unknown reasons, according to authorities and sources.
The brute then stabbed the straphanger in the lower back, causing puncture wounds, police said.
The wounded man was taken to Bellevue Hospital, where he was listed in stable condition, cops said.
Meanwhile, the attacker – who had no relationship to the victim and was only described as a male with a light complexion – fled the scene, cops and sources said.
The assailant had not been caught hours later, and no information was immediately available on what the fight was over.