The finest book ever written about boxing imho was this, by the great George Plimpton, who has long been a hero of idle's combining as he does a love of literature, sport, journalism and the human condition. A supreme stylist and a great American man of letters, right up there with Alastair Cooke in terms of style and sagacity.
Plimpton knew Muhammad Ali, warts and all, and thought him exceptional. The Tuscan has a low opinion; perhaps he's seen When We Were Kings - if not, see it - but read this book and you might see Ali in a different light. Possibly the best book ever written about sport.