A stranger punched a man in the face in an unprovoked attack on a Downtown Brooklyn street early Wednesday, cops said. 

The 67-year-old victim was walking on Willoughby Street near Lawrence Street – steps from the Jay Street-MetroTech subway station – around 7 a.m. when the brute suddenly slugged him without saying a word, police said. 

The impact caused the victim to hit his head on a parked car and on the pavement, cops said. 

The victim was taken to NYU Langone Hospital-Brooklyn, where he was listed in stable condition, police said. 

The suspect, described as a man with a dark complexion and a slim build – between 25 and 35 years old and around 6 feet tall – fled the scene. 

He was last seen wearing a black mask, black hooded sweatshirt with a graphic and the word “Tokyo” on the front, black sweatpants, white socks and black slippers.

Video released late Wednesday shows him throwing something into the street, toward a moving car, as he walked on the sidewalk.