Joe Cortez, who refereed four of Floyd Mayweather's bouts, has gone against most boxing analysts' predictions by saying Conor McGregor might win tonight's mega-bout.
Speaking to Press Association Sport, per Boxing Scene, Cortez, who helped familiarise McGregor with the Queensbury rules, cited the two-weight UFC champion's attention to detail and confidence, as well as an ageing Mayweather, as reasons to expect an upset.
"He has a good punch and a lot of, confidence in himself. His conditioning is superb, so you've got to give him a chance," Cortez said. "Absolutely a good chance. He can punch, and he's not going to be afraid to go in there and mix it up if he has to.
"He would probably be a world champion. If he was a good as he is in MMA he would definitely be a world champion, he's got all the ingredients to be an excellent, excellent fighter.
"He has what it takes to be very successful Saturday night.
"(Mayweather's) 40 years old now, so he's not a young Mayweather anymore. In boxing we all know that you can get old overnight, so we'll have to see which Mayweather comes out."
Cortez is one of the few people from the boxing world to speak so optimistically in favour of McGregor.
Most predict a one-sided fight between 49-0 Mayweather, one of the greatest technical boxers of his time, and an MMA fighter who, whilst a brilliant striker in his home sport, has never had a single professional boxing match.
But Cortez is also one of the only people from the world of boxing with an intimate insight into McGregor's preparation for the fight.
He helped train McGregor for six weeks during the Irishman's camp. And what he saw impressed him.
Cortez added: "He's improved a lot from day one. He's a quick learner, I was impressed with how quickly he learnt, but that's why he's a champion in MMA, because he has something different that other people don't have."