Originally posted by: basey44
watever aizen is obviously the waekest of the captains, he even wear glasses and has funny hair
Actually, there's not much emphasis on which captain is the strongest. Looks can be deceptive.
Still, based on what they've been saying so far, it seems that only a captain can fight on equal grounds with another. Also, if you put in the element of surprise, then it's possible that someone could've easily taken Aizen's life.