i find it funny how everyone is saying "WTF!!! Sasuke shouldn't be able to beat itachi", but wait isn't sasuke pretty much the second main character of Naruto? what did u think will happen of course he will be able to fight his brother which has been his whole story thus far, find his brother and kill him. Also it was only one part of the MS that itachi has used, which he used on sasuke before. Maybe just maybe sasuke trained himself to fight that technique since he knew itachi would use it? Oh wait the clay dude (i forgot his name dieadora or something like that) did the same thing, he trained his eye to fight gengutsu.

The reason sasuke is healed after fighting the clay guy is because of the healing powers he gained from taking in oro. he said it after the fight that he was amazed at how fast he was recovering, u just need to look back and it was explained why he is healed.

It might not happen now, but it will happen before naruto is over Sasuke will kill Itachi, and it aint cause kishi loves him it's because that was sasukes goal/character desighn from the begining of this manga. On another note, Sasuke still hasn't used the technique oro told him not to use on naruto, i doubt it was the shuricans or manda summon lol.