Tuesday Morning Brain Teaser!

It's time for your Tuesday Morning Brain Teaser!  No cheating!  Let's see how good your memory is from 1990!

I know we have interns here at the radio station who weren't born yet, but it was still a pretty big event.  Here is the question:

What 42-to-1 underdog KO'd Mike Tyson in Tokyo in 1990?  I'll even give you a hint:  no ear biting was involved!

Good Luck!