American Poirier became the first fighter to knock Irishman McGregor out in January, during an Abu Dhabi-hosted fight. McGregor and Poirier were supposed to face off for the third time as part of a trilogy fight this summer.
But McGregor on Monday launched into an expletive-laced rant directed at Poirier, after the American accused him of not keeping his word about donating $500,000 to his charity.
“We thanked him because his team reached out fight week to initiate the process but ghosted us the past two months after the fight.
"My foundation has reached out three times since with no reply. We've moved past it! We will be announcing our next goal soon! It’s a big one,” wrote Poirier on Twitter, tagging McGregor and claiming “you and your team stopped responding after the fight in January.”
McGregor didn’t take kindly to the claims and called Poirier “braindead” among other insults. He also said he would no longer fight him on July 10.
“Donation, not a debt. We’ve been awaiting the plans for the money that never came. I do with all my donations. Know where it’s going dot for dot. Otherwise it goes walking,” McGregor said in a reply.
“500k with no plan in place. Ye hang tight. Fool. You must be new to money. The fight is off [by the way]. I’m going to fight someone else on the 10th. Good luck on your old contract kid,” he continued.
Poirier responded simply with “ok” and a gif of the moment he knocked McGregor out.