“Do I Have The Heart To Stick Him?”

When a teenager looking for a ​“knockout” took a swing at a grocery store worker, the attacker and his friends found themselves facing down a knife blade.

That was the scene outside Elm City Market, where a group of teens on bikes set upon the co-op’s cheese and bakery manager, Robin Williams.

One teen punched Williams in the mouth. A scuffle ensued. Williams found the group advancing on him yelling threats.

As he backed away, Williams pulled out a folding knife to defend himself. As the teens kept coming, he faced a question: Would he defend himself? Would he use his knife against a teenager?

The incident may be part of a recent trend of teenagers playing a vicious game called ​“Knockout,” in which young men punch random strangers in the face for fun. Police this week took reports of six possible ​“Knockout” incidents in two days.

Yale police Chief Ronnell Higgins sent out a warning on Thursday, urging people to take precautions, like not walking alone after dark and being aware of one’s surroundings. New Haven police spokesman Officer David Hartman said Friday that police have identified three ​“persons of interest” related to the six incidents. Detectives are investigating all of the reports, using social media as well as traditional methods. Hartman said undercover plainclothes cops have been deployed to several areas of the city to try to catch the perpetrators.

The attack on Williams may be a seventh ​“Knockout” incident.

Here’s what Williams (pictured), who’s 47, said happened:

Just after 1 p.m. on Sunday, Williams and a co-worker were outside Elm City Market at the corner of State and Chapel streets. They’d just picked up coffee at Dunkin Donuts across the street and were finishing cigarettes before returning to work.

A group of four or five teenagers on bikes came down Chapel, headed toward State. Some were riding in the street, some on the sidewalk.

One teen, a ​“wild, blonde-haired kid,” passed close to Williams. ​“I turned to say, ​‘Hey, what’s up, man?’ He hit me right in my mouth.”

It wasn’t a forceful punch, Williams said. ​“He barely swole my lip.” Then the group of teens started riding off. They didn’t try to rob Williams.

Williams turned and realized he could still grab his assailant, rolling away on his bike. He ran after the teen, who swerved into the street and crashed into another one of the bikers.

That gave Williams the opportunity to grab the guy who had hit him. ​“As soon as I grabbed him, we both fell.”

Williams found himself down on the pavement in Chapel Street, scrambling backward as he saw a line of teens advancing on him. His co-worker grabbed one of the teenagers and shoved him, giving Williams an opening to dart onto the sidewalk.

Williams told his co-worker to run inside. He started ​“backpedaling very quickly” down the Chapel Street sidewalk as the teens came at him.

Williams pulled out the folding knife (pictured) he keeps in his right pocket. He said he uses it to open boxes in the store.

One of the teens noticed the blade. ​“He’s got a knife!” the teen shouted.

Three of the teens stopped; one was still ​“coming hard,” yelling, ​“Oh, you want to fight?”

“I got to the point where I realized: This kid isn’t going to stop,” Williams said. He realized he might have to use his knife to defend himself.

“Do I have the heart to stick him?” Williams thought to himself. ​“This kid here, he just ain’t stopping.”

Williams said he didn’t know the answer to his question.

Luckily, he didn’t have to find out what it would be.

“As soon as I thought that, he turned around,” Williams said. The teens left, and WIlliams went back inside the grocery store.

“It was scary at the time,” Williams said. ​“I came in and was just mad about it.”

Williams called the police, who came and took a report.

Williams said he thinks the attack was ​“just a random act of violence,” just kids ​“looking for a thrill.”

Williams said he has seen videos of ​“Knockout” attacks. In those videos, the punchers were on foot. ​“This guy’s on a bike, he ain’t got no leverage” to punch hard.

If it was ​“Knockout,” his attacker wasn’t doing it very well, Williams said.

Williams said he knows to be wary of groups of teenagers on bikes, but he never expected to be attacked downtown on a Sunday afternoon.

He said he still doesn’t know what he would have done if the teenager had kept advancing. Would he have used his knife?

“If he had come, a decision would have had to have been made,” Williams said.

The encounter could have ended tragically, he observed ​“I’ve been dealing with that for the past couple of days.”