I'll humor you itachi fans, lets just say somehow itachi miraculously catches Naruto in tsukuyomi. 3 seconds is the equivalent of three days in itachi's genjutsu. Naruto has the ability to separate from Kurama at will whilst maintaining telepathic communication as their spirits are now one. Basically Naruto has the power to insta summon Kurama. Heres how the battle would play out assuming Naruto is caught.
Itachi: Cast tsukuyomi
Naruto: Senses he's in gen, tells kurama to end it.
Kurama: Insta Appears on battle field and Begins to slam tail on itachi
Itachi: Fatigue/Aids kick in from gen usage, gets demolished by kurama tail GG
Even if tsukuyomi wasn't interrupted Naruto wouldn't be phased, he survived bijuu extraction for godsake.
Honestly the moment Naruto gained SM he could fight blind/eyes closed, mixed with kurama negative emotion sensing + unrivaled reflexes he's one of the few people who can defeat itachi eyes closed.
Itachi: Cast tsukuyomi
Naruto: Senses he's in gen, tells kurama to end it.
Kurama: Insta Appears on battle field and Begins to slam tail on itachi
Itachi: Fatigue/Aids kick in from gen usage, gets demolished by kurama tail GG
Even if tsukuyomi wasn't interrupted Naruto wouldn't be phased, he survived bijuu extraction for godsake.
Honestly the moment Naruto gained SM he could fight blind/eyes closed, mixed with kurama negative emotion sensing + unrivaled reflexes he's one of the few people who can defeat itachi eyes closed.