Or so the story goes, anyway.
McGregor and Malignaggi famously fell out in August 2017, after leaked footage emerged on social media showing Notorious dropping his sparring partner several times in training.
It came after Malignaggi came out of retirement to help the Irishman prepare for his mega-rich bout with Mayweather, which was billed as 'The Biggest Fight in Combat Sports History'.
The former world champion reportedly stormed out of the camp following the incident, as he described McGregor as a 'scumbag' and 'one of the biggest dirtbags I've ever met'.
While Malignaggi has always vehemently denied these claims, a source told CBS' combat sports analyst Luke Thomas that McGregor 'whooped' Malignaggi.
It shows McGregor, in full protective gear, lighting up and dropping his sparring partner.
After Malignaggi falls to the ground, McGregor casually swaggers towards him, with his hands down by his side in an act of total disrespect.
Check out the video below:
It doesn't look good for Paulie, does it?
Malignaggi has never forgiven McGregor for breaking the first rule of fight club, and has long sought his revenge.
Insisting 'there's more than enough money in the pot', he told SiriusXM: "I mean, I wouldn't put it past anything but I don't think Conor McGregor is ever going to want to fight me.
"The only way that I'd fight Conor McGregor is if it's winner-takes-all at this point. I wouldn't fight Conor McGregor, there wouldn't be any kind of negotiations it's either winner-takes-all or we don't fight.
"At this point he's got everybody convinced he's better and there's more than enough money in the pot. He makes more money fighting me than anybody else other than maybe Jake Paul. So, I don't see him taking that kind of deal, so there's probably not going to be a fight."
Can you get full marks on the ultimate Conor McGregor quiz? 17/20 is the score to beat.