How??? is what you are thinking, well let me tell you.
Thats how simple it is, not only that he has back up with totsuka blitz.
On top of that, what could Obito do to Yata Mirror?
Along with the fact that as soon as they talk to each other (Which they would do as he spoke to Naruto loads) he could Genjutsu him and it's OVER!!
Simply put, Itachi STILL SOLO'S