The Rangers fan who knocked out a rival Tampa Bay Lightning supporter at Madison Square Garden on Thursday night told police hours later he was worried the attack would go viral, it was revealed at his arraignment.

“This may be on the Internet. Oh f—k,” 29-year-old James Anastasio said to an officer at the Midtown South Precinct after he was caught on camera sucker-punching the victim in the hallway of The Garden after the game ended, Manhattan Assistant District Attorney Hannah Dionne said at the early Saturday morning hearing.

The Lightning fan was left unconscious on the concourse floor and video of the brutal beatdown did indeed make its rounds on the internet.

Anastasio, of Staten Island, was freed on supervised release at his arraignment and ordered to stay away from the Lighting fan he allegedly assaulted and a second man he’s accused of attacking after that man tried to stop him from fleeing.

During his court appearance, Anastasio wore the same red Rangers “Panarin” T-shirt and gray sweatpants he was seen wearing in footage of the attack.

Anastasio, who has been banned from The Garden for life, refused to comment as he was led out Manhattan Criminal Court by his lawyer.

Earlier Friday, his father, also James Anastasio, told The Post Friday that his son “made a choice.”

“There’s nothing to defend. It is what it is. We’ll wait for him to come home, we’ll pick him up, and everything’s OK. Tomorrow’s a new day.”

The younger Anastasio is scheduled to appear in court again on June 29.