Board Thread:Theories and Speculation/@comment-31338621-20180506051005/@comment-32685487-20180507214636

Itachi was near death and almost blind, him being able to use the full capacity of his ms techs is highly doubtful. Zetsu even commented something was wrong with him. So lets assume it wasn't a full powered usage.. Sasuke still broke it with his Sharingan, meaning with his MS he should be able to break Tsukuyomi at full force.