The victim was walking on Sunday around 9pm with a friend to his car, parked a few dozen metres from the Portuguese grill he owns on the Rue de Carouge, when he came across the thief in his vehicle, the 20 Minutes newspaper reported on its internet site.
“He notably took a slash of the knife to the neck,” a waitress at the restaurant told the newspaper, describing the way her boss was attacked.
Staff at the restaurant said the owner was in a coma and “there is no hope”, 20 Minutes said.
The waitress said the restaurant owner had “a moneybag and cash inside the car”.
The restaurant owner’s friend received a knife wound to the hand after trying to intervene, the newspaper said.
The report cited waitresses from the Portuguese restaurant and another bistro nearby who said the attacker was an English speaker.
The two men attacked were taken to hospital.
Police are remaining tight-lipped about the case, which was under investigation by the prosecutor’s office.