It appears that Putin and McGregor crossed paths at the Luzhniki Stadium and the Dubliner had nothing but nice things to say about the controversial Russian president.
"Today was an honour for me Mr Putin".
McGregor then signed off his message with "Россия вперёд!", which translates to "Go Russia!"
Mashable has reached out to McGregor's representatives for comment.
The former UFC champion paid tribute to "one of the greatest leaders of our time" Vladimir Putin while attending Sunday's World Cup Final between France and Croatia in Moscow. Unless you consider leading by fear and murder is considered great.
Who do you think wins if this fight is booked, Conor or Khabib?
The BBC's Tom English simply replied to McGregor with, "Puppet".
Predictably, from the man who is never shy about weighing in with his opinions on global matters, U.S. President Donald Trump also offered his congratulations to France, and ... to Russian President Vladimir Putin.
McGregor made a court apperance last month after he was charged with several crimes following an April bus attack.
Conor McGregor is as credible as they come right? His next court appearance is set for July 26.
The two fighters have been engaged in a war of words amid rumours a fight is in the works. But, the football spectacle also had something for the MMA fans too.
"What's happening, Pogba?" McGregor said.