You are too young probably to young to remember the "Thrilla in Manila", Ali v. Frazier, 1975.
I listened to it on the radio. I remember listening to parts of it on the bus on the way home from school.
Then there was the famous Frazier v. George Foreman fight, 1973.
"Down goes Frazier, down goes Frazier ! "
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After that era I just lost interest. There was Tyson of course, but he was who he was...