Amir Khan could fight a milkman and it would still be a risky fight!
We have to give Khan a lot of credit for fighting someone who possesses a 60% KO ratio in Julio Diaz. As we all know, Khan has the worst chin in boxing, and has even had his legs stiffened by strong gusts of air, so I don't see any problem with him taking a supposed 'lesser challenge' in Diaz. I really wouldn't want to stay up all night just to see Maidana, Matthysse, Peterson, or Garcia blow him out in 30 seconds. It's just not worth it! By my reasoning, Khan - Diaz should at least go 6 rounds if Khan can backpeddle enough, though he'll probably be KO'd by the first big shot that lands. Make no mistake, Diaz is the huge favourite going into this fight - with a 60% KO ratio you just can't dispute that he has the tools to beat Khan quite comfortably.
Good luck to Khan in surviving till the bell ends. That alone will be a victory in itself. Can't wait!!!