Muhammad Ali and Ken Norton fought three boxing matches in the seventies. Ali lost the first one in 1973 and wound up with a broken jaw. Ali barely won the second later that year. The third took place in 1976 and ended in the controversial decision. The judges awarded the victory to Ali but even he said he thought he lost.
On 9/07/1973, three days before the second match, Norton and Ali appeared with Johnny Carson on The Tonight Show for some banter, some attempted psyching-out of each other and a ceremonial, unofficial "weigh-in."
This runs twenty minutes but it's kind of interesting as an example of the charisma that Ali brought to his career. You kind of understand why so many people rooted for this guy. You also see Mr. Carson's expertise in handling a segment where little could have been planned in advance…