Monster fines have been handed out to those who have plastered the pay-per-view content over the internet in the past.
Tonight’s giant clash at London’s O2 Arena on Saturday is being sold on ITV Box Office for £19.95.
Anyone who attempts to film and stream it for other viewers could be slapped with a huge penalty.
Those sharing with friends over social media are also being warned not to take the risk.
Craig Foster from Scarborough was handed a mammoth £85,000 bill when his friend broadcast the Anthony Joshua vs Wladimir Klitschko fight, last year.
He was prosecuted because the friend then illegally broadcast it via Facebook to 4,250 people via Foster’s iPad.
The 34-year-old was found using a watermark of his account number.
Sky charged him for loss of earnings.
“I’d paid for the boxing, it wasn’t like I was making any money,” Foster told the Mirror at the time .
“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 round that night but I’m not going to give them up. I said I’d take the rap.”
Security experts also warned against streams because of the risk to the safety of your PC.
Some streams will hide malware which could infect PCs and laptops.