A blonde bruiser laid out a Manhattan dogwalker with a single punch to a the jaw when the man snapped at him for stepping over his white Chihuahua, a shocking video shows.

Paul Martone, 49, was walking little Peanuts at West 55th Street and Ninth Avenue at around 6:30 p.m. Tuesday when the hot-head committed the faux pas of walking over the pooch instead of around him.

Martone, with his stocky boyfriend standing nearby, yelled at the man — who tried to walk away.

“The suspect was trying to remove himself from the situation, and walk away,” according to one law enforcement source.

But Martone would not relent, egging on the victim with the taunt, “Why don’t you throw the first punch?”

The suspect took the bait and landed a vicious right hook into Martone’s chin — and walked off as Martone fell backward and cracked his head on the sidewalk.

The attack, which was taped by a passer-by, left the bartender Martone in critical condition at New York-Presbyterian Hospital’s Intensive Care Unit, police sources said.

The suspect — a known neighborhood thug who illegally rents bikes to tourists in Central Park — was still on the loose Wednesday evening.

“He’s been a complete menace,” Chris Wogas, president of rival bike rental company Bike and Roll, complained of the berserk blonde.

“He’s threatened our security. He’s threatened our marketing manager to the point where she had to file a police report .”

Soon after police released the chilling video, Bike and Roll workers called 911 to tell cops he is the same man who steals their business.

“I felt very unsafe,” marketing manager, Nicole Mylonas, 24, said Wednesday, recalling an incident two weeks ago when the suspect confronted her as she photographed the company’s advertising kiosks.

Meanwhile, Martone’s bodybuilder boyfriend, Miguel DeContreras, trembled as a neighbor asked if Martone was going to be alright.

“I don’t know,” he answered.

Additional reporting by Georgett Roberts, Larry Celona and Antonio Antenucci