Right now, four people are in custody after this latest incident in Borough Park.
The victim was rushed from the 66th precinct moments before sundown, the start of the Jewish Sabbath.
He was walking alone on 18th Avenue at 2:30 in the morning when he was confronted by four men.
"Did they say it was part of the 'Knockout Game?" Eyewitness News asked.
The victim said on the phone that there was no question about it, and he told detectives that the assailants seemed to be daring one another to punch him out.
"He makes a statement that he was punched in the side of the face. He also makes a statement that just prior to it they were talking about the 'Knockout Game,'" Police Commissioner Ray Kelly said.
The four men were arrested within minutes of the assault.
Patrols have been stepped-up in several Brooklyn neighborhoods where many of the victims have been Jewish and may have been targeted in an emerging national trend.
The object is to knock someone unconscious with one punch. It's what happened to a schoolteacher in Pittsburg last year, and might have been the motive behind a similar attack on a 78-year-old woman in Midwood earlier this month.