Board Thread:Versus Debates/@comment-24824859-20151125011733/@comment-26369387-20151212021311

Ishi208 wrote: Questions: Where does Gaara not block base chidori? Part 1? And if Sasuke has OP Genjutsu then why didn't he use it on Naruto?

During the finals of Chūnin Exams, Sasuke pierced Gaara's sand sphere with Chidori.

As for why Sasuke didn't use genjutsu against Naruto was probably because as it was seen during the fight between B and Taka, jinchūriki can be released from genjutsu thanks to tailed beast inside them. So it's possible Sasuke thought using genjutsu would be waste of chakra.