Would've Loved MMA, McGregor

Ali-Walsh will make his Professional Fighters League debut on November 25 ... and fittingly, it's going down at Madison Square Garden.

Of course, MSG was the site of many of Ali's legendary fights ... including the "Fight of the Century," Muhammad Ali vs. Joe Frazier I on March 8, 1971.

We asked Biaggio about fighting under the same roof as grandpa ... and while he thinks it's pretty neat, he was honest in saying it's not a huge deal.

"I think it's cool but at the end of the day, a fight's a fight. It's me, the ref, and another guy who's trying to hurt me, whether it's Madison Square Garden or in the back of someone's barnyard. It's cool that it's at Madison Square Garden but I don't care,…