I believe Bruce Lee would beat Ali in a fight if Ali had to wear boxing gloves and Lee were allowed to kick. In a street fight, I would still give Lee the edge if Ali had no ground game, but Lee did, as 95% of fights end up with opponents getting entangled with each other. A smaller guy with ground skills will beat a bigger guy without ground skills. Submissions, choke holds, riding one’s opponent until they get winded, and taking their opponent’s legs out from under them are advantages the martial artist has over a opponent who only knows boxing. Sure Ali has world class abilities with the weight and reach advantage. But time and time again we have seen pure boxers get beat decisively by smaller martial artists and ground guys on UFC.
I have experienced getting beaten by a shorter state champion wrestler several times that I outweighed by about 35%. I also knew basic wrestling moves. Although my opponent was stronger than me and could bench press twice his body weight, he made it a point not to use his superior strength against me and relied on technique instead. No need for me to feel too bad because on several occasions my opponent had crushed people twice his weight in bar fights.
I knew an American Muay Thai fighter at Gold’s Gym in Naples, FL. He demonstrated the “1 inch” punch and knife fighting techniques. It was astonishing how hard he could hit with his fist just by snapping his wrist. Actually, his 1” punch involved precisely timing the movement of his hips as well. Underestimate martial artists, including Jiu Jitsu and wrestlers at your own risk.