Board Thread:Versus Debates/@comment-142748-20150410212019/@comment-142748-20150411235634

QuakingStar wrote: He was very sick the entire fight, Black Zetsu even said he was overall slower and his reflexes were slower compared to his normal self, then said Itachi should be much better, much stronger. It got fatal around the time he used Susanoo, his organs were failing hence the blood coughing, holding his heart like he had a heart attack and subsequently dying. He was also just about blind when Kirin was used. I'm not doubting he was sick during the fight, what I'm saying the severity increased when he used Susanoo.

Itachi's best we saw in life was in Part I, which had three Mangekyo Sharingan usages. Think about it, he had to rush everything to face Sasuke in Part II, if he was sick all along why would he have to rush at all?