Board Thread:Theories and Speculation/@comment-31099706-20170327120301/@comment-734582-20170521123544

Kakashisologod1 wrote: Just like sasuke saw through itachis illusions?He was blinded by hatred. Sasuke saw through several layers of his Genjutsu. Which proves that Itachi was in fact being serious.

In contrast, Sasuke didn't notice Itachi being too slow (which Zetsu did notice) because he's never fought his brother like that.