UFC president Dana White released several videos on Friday of McGregor sparring with Paulie Malignaggi. Malignaggi is a former IBF and WBA World Champion.
The session occurred on Aug. 1.
Malignaggi later quit as McGregor's partner after a photo surfaced showing him falling back after being hit by McGregor.
"He tried his best, but he got his [expletive] whupped," McGregor told ESPN. "Tell me how his face looked. Tell me how his temple looked. He was badly, badly concussed after those rounds. Badly rattled. He was flattened and knocked down. The ropes kept him up multiple times."
"Sparring partners who were [staying] in the house with him were worried about him. They were ringing us, worried about him stumbling out of the car, incoherent."
"I don't know what happened. At the end of the day, we got in and traded blows, so I respect him for coming in. It didn't go well for him. I don't know why he sprinted out of there. His ego was dented."
Malignaggi claims that he was pulled or pushed down to the canvas during the sessions, an illegal move in boxing.
"Here is the video everyone wanted to see of Conor vs Paulie Malignaggi former IBF and WBA World Champion," White tweeted Friday.
"For all the people who think @TheNotoriousMMA can't box. This is gonna be a FIGHT! Conor vs Paulie Malignaggi former IBF/WBA World Champion," White added.
Malignaggi responded to the video, explaining why he fell.
"The guy won 2 rounds outta 12, there were no problems aside from me fatiguing at end I assure you lol," Malignaggi tweeted.
"I've put up 2 slowmo replays I can't show more than that," Malignaggi tweeted. "His left overshoot n winds up on my neck, inside he misses hook, not 1 punch lands."
"I think it's clear I'm being pushed down by back of my neck any[one] that what's to see it will [see] it. Out of 36 minutes they have 45 seconds lol," Malignaggi tweeted.
McGregor and Mayweather battle on Aug. 26 in Las Vegas.