Dad-of-one Craig Foster, 34, was watching Joshua’s fight against Wladimir Kiltschko on his TV in April and had shelled out £19.95 to Sky for the pleasure.
But as the sell-out Wembley fixture started, one of his friends picked up Craig’s iPad, started recording over Facebook Live and pointed it at his TV.
He ended up streaming the big fight to more than 4,000 people, with Sky eventually tracking Craig down from a watermark of his account number which flashed up on screen.
Sky cancelled his subscription and sent him an £85,000 bill for the loss in revenue from pay-per-view sales.
Dad-of-one Craig said: “I’d paid for the boxing, it wasn’t like I was making any money.
“My iPad was signed in to my Facebook account and my friend just started streaming the fight. I didn’t think anything of it, then a few days later, they cut my subscription.
“They’re demanding the names and addresses of all my mates who were around that night, but I’m not going to give them up. I said I’d take the rap.”
More than 400,000 people used Facebook to watch illegal live streams of the fight, which saw Joshua beat Klitschko in the 11th round.
The social media giant faced criticisms, as it was claimed it cost Sky millions in lost revenue.
Craig said: “They’re making an example of me. I know streaming the fight was wrong. I didn’t stop my friend, but I was watching the boxing.
“I’m just a bloke who had a few drinks with his friends.”
Craig, of Scarborough, North Yorkshire, says he has been bombarded with letters from law firm Foot Anstey LLP, which represents Sky.
One ordered him to pay £5,000 in legal costs or face court over the full amount. It said the “unlawful redistribution of [Sky’s] content is a serious matter which has a significant impact on its business.”
The letter also demanded an apology “to use in education materials concerning unlawful redistribution of programmes.”
The coach builder apologised and said he agreed to the demand in a panic, claiming he was given only 24 hours to seek advice – but now plans to fight it in court.
“Everyone is saying it’s wrong what they have done,” Craig said. “It’s heavy-handed. I’ve apologised and told them we were drunk.”
Neil Parkes, of Foot Anstey, said: “Mr Foster broke the law. He has acknowledged his wrongdoing, apologised and signed a legally binding agreement to pay a sum of £5,000 to Sky.”
The maximum jail term for copyright infringement is up to 10 years in jail and/or an unlimited fine.