Mike Tyson still has his fighting spirit and is putting his peers on notice.

The heavyweight boxing legend was a guest on The Tonight Show Starring Jimmy Fallon on Monday (July 27) and discussed coming out of retirement for an upcoming fight with world championship boxer Roy Jones Jr.

"I'm back, man, I'm back. I don't know how it came back. I started training, I'm back in shape, 228 [pounds],” he said. “I've been boxing, I can't believe this either, man. I don't believe in the fountain of youth, but something just came over me and I'm back, man.”

Last week, it was announced that Tyson, 54 and Jones, 51 will be fighting in an eight-round exhibition bout on September 12. The event is part of the launch of Tyson’s new “Legends Only League,” which will bring back the “best of the best” boxers in each category. Tyson however believes he still has what it takes to beat anyone.

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When asked about fighting 32-year old, Irish retired boxer and Ultimate Fighting Champion Conor McGregor, who primarily squares off in MMA matches, Tyson stated that McGregor is “nuts” and said, "Yeah, but I'm going to kick his ass anyway."

While Tyson claims he would beat McGregor, there is one legend, albeit fictional, that Tyson says he would totally not mess with if ever caught in front of him. 

"Whoa. Wax off, wax on,” he said speaking of the Karate Kid. “This looks pretty complicated. I'm going to have to surrender to him on this one.”

Watch the full interview below.