A Brooklyn man will remain jailed on charges he attacked a fellow casino patron with a chair and a knife, leaving the victim needing emergency surgery to close a slash to his face.

Keontay Long, 26, was arrested last week along with two friends who are accused of helping in the attack.

The incident began with a verbal argument at Harrah’s Atlantic City just before 4 a.m. July 13.

Long is seen in video grabbing a high-top chair from the casino floor and throwing it at the victim, who is struck in the head, according to the affidavit of probable cause read at his detention hearing Monday.

The victim tries to run away, but is tackled by Long, whose two friends then hold the man down while Long cuts his face with using a folding knife with a red handle, the complaint states.

Defense attorney Andrew Imperiale argued that “there’s two sides to the story,” indicating the victim may have been the aggressor.

“Once more discovery is released, those arguments will happen at a later time,” he told the judge.

He pointed out that Long has no criminal history, according to his public safety assessment, noting that none of the charges against his client shift the case to presumed detention.

Long is an expectant father who works two jobs: one in the electrical field and one in pursuit of a music career, Imperiale said.

The defense included character letters from both employers, along with ones from a friend and the maternal grandmother of Long’s future child.

“He’s never been in trouble before,” Imperiale said.

But Judge William Miller was struck by the violent nature of the allegations, including the video that reportedly shows Long running after and tackling the retreating victim.

“Retreating, emphasis by the court,” the judge said. “After (the victim) attempted to retreat, he was sliced in the face. Sounds pretty defenseless in terms of the victim.

“Sounds like there was plenty of opportunity to retreat on both sides,” he continued. “Again, this victim was retreating.”

Miller questioned why someone would have a knife on the casino floor, saying there were “lots of aggravating factors here, to say the least.”

“To me, this is a 26-year-old with no history but why in God’s name would you hold somebody down and cut their face?” the judge asked.

Kevan Winkle, one of Long’s co-defendants, was released Friday, following his detention hearing.

A third man, Tori Sylvanus, was charged with simple assault and released on a summons without being jailed.

Imperiale was going to talk to Long’s family about possibly filing an appeal.