The Last Great Fight by Joe Layden
Just finished reading this and it's fantastic, especially if like you grew up around the time of Tyson.
It's takes you inside the Mike Tyson/Buster Douglas fight in Tokyo in February 1990. Very thorough and well researched, Layden really cares about the subject matter (in particular Buster Douglas) and I got through it in a day.
I can really recommend it!
On another note, reading the book I had the thought that next February will the 20th anniversary of Douglas/Tyson. Fuck I feel old:o