Oscar De La Hoya says Floyd Mayweather would outclass Conor McGregor but a fight between the two would be an embarrassment for boxing and mixed martial arts.
Rumblings of a bout between multiple weight world champion Mayweather and UFC champion McGregor continue, with both sides having talked up a cross-code showdown for a number of months.
But De La Hoya feels McGregor's lack of professional boxing experience would make for serious safety concerns and believes it would be better if each man stuck to their respective discipline.
Mayweather, now 40, has not fought since beating Andre Berto in September 2015 to make it 49 wins from 49.
De La Hoya said: "Boxing is boxing and MMA is MMA. They're two separate sports. It would be a joke, it would be an embarrassment for boxing if an MMA fighter were to go into the ring, it would be a no contest.
"It would be the same thing if a fighter went into the octagon. It would be an embarrassment for MMA.
"I just feel that these are two separate sports and you have McGregor who is the best at what he does, and you have Mayweather who is the best at what he does. I don't see this fight taking place, not in a million years.
"Not only are there safety issues, but if McGregor gets in a boxing ring he'll get outclassed easily. McGregor has never fought a boxer ever in his life. It's a whole different sport.
"When you cannot kick, when you cannot clinch, when you cannot do the armbar, when you cannot choke somebody out and you can only punch, it's a whole different sport, it's a whole different discipline.
"What McGregor should do, in all seriousness, is he should start off by fighting an amateur boxer, win a few amateur fights, maybe go on to win the Golden Gloves.
"And then when he turns pro he should fight a four-rounder, maybe he'll get beat, but he should get experience in boxing. Then call out the best. You cannot be calling out a top fighter in boxing right off the bat."