Board Thread:Theories and Speculation/@comment-26358288-20150630121218/@comment-5273810-20150630213930

QuakingStar wrote: Black Zetsu DID say he wasn't fighting at his best all around. He was sick and near death too. I'm positive if Itachi wanted to actually kill Sasuke there, he would not have got out of Tsukuyomi, and he would of then had his eyes plucked and then incinerated to ash. Black Zetsu did say that he wasn't fighting at his best but only AFTER the Genjutsu part of the fight was done. Which can be interpreted as Itachi did go full out during the Genjutsu bit but not during the Ninjutsu bit. If you want to believe that Sasuke couldn't break out of Tsyuchiomi if Itachi didn't want him to, that is fine. Its your decision. It is unprovable either way as I noted earlier.

But, if you notice in my first comment, the proof I had wasn't that fight, it was actually the fight with Kabuto where, Itachi could only break the Genjutsu with Tsuychiomi while Sasuke could with just Sharingan Genjutsu.