not that Sasuke can't beat Itachi, but i wouldn't be surprised to see Sasuke lose simply from being to busy wanking on Itachi to actually fight. Dude had EMS and somehow still found the time for Itachi wanking.
Sasuke did that because he knew that at that moment he was still weaker than both Itachi and Kabuto in that cave. He didn't truly surpass Itachi or show what he could do until he got to the battlefield.
ot: Sasuke cannot teleport and you misinterpreted the latest chapter. He has increased speed and can see Madara's other half...that's all.
Btw, Yata mirror deflects all attacks, including astral bodies. So not even any s/t jutsu can affect it. Kishimoto didn't really bother to give it any limits. Also, since Itachi is an edo, Sasuke would have to seal him...when he has not a single sealing feat. Itachi takes this.