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The Notorious fighter is known for his scarily accurate 'Mystic Mac' predictions but went a step further and wanted to get some money involved back in 2015.
McGregor's fight with featherweight champion Jose Aldo was nixed after the Brazilian pulled out following a rib injury. Chad Mendes was the replacement for the UFC 189.
The Irishman had to prepare for a completely different opponent on incredibly short notice but his belief in his ability did not wane.
As per The Mirror, White recalled: "You want to know how confident this kid is? I can't even believe I'm going to say this, but, he told Lorenzo and I the other day, 'I'll bet you $3 million I knock him out in the second round.'
"I like to bet, I don't know if I'm that willing to take that bet. When I tell you how extremely confident this guy is in himself, it's fascinating. He is a very unique, fascinating person to listen to. Fun to listen to, and fun to watch."
Much like he has done on a number of occasions, McGregor called it perfectly. Three months after tearing his ACL, he put Mendes away in the second round to claim the interim featherweight championship.
McGregor would then go one better as just five months later he knocked out original opponent Aldo inside 13 seconds in stunning fashion to become featherweight champion at UFC 194.
Celebrating the five-year anniversary of the KO in December, McGregor shared rare footage of him practicing and envisioning the very same deadly left hand that scored him the victory.
In terms of his upcoming bout with Dustin Poirier at UFC 257 this weekend, McGregor reckons he will knock 'The Diamond' out quicker than he did in their first bout at UFC 178.
McGregor has promised "a masterpiece" and believes he will secure the knockout inside "60 seconds".
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