because with the amount of money in the pot.. the information you've presented.. (opponent is tired.. and thats the only read you've presented).. there are any number of 2nd best hands that he can have here.

everybody says check call the river.. im almost inclined to say bet into the non-diamond river for value.. if he raises you have to call unless you're SURE he has AA. chances are he has AdKd or AJ and possibly 88.

take advantage of the tired guys! they may be good players but if hes really tired he might not give you credit for a better set here.. talking himself out of it.