Before their fight did kakashi know that itachi had the MS

[Zavage10]

I don't feel like searching

 

[Invsblphntm]

I believe so, that's probably why he so insistent on everyone closing their eyes, even Kurenai, a Genjutsu expert.

 

[Kuroh]

maybe or maybe not but he semmed somewhat shocked when itachi reveled he had ms

 

[Byakuya K]

kakashi knew that itachi was more than just a master of the regular sharingan.

 

[Zavage10]

I remember kakashi claiming that itachi was on fighting at 50 percent, but he showed true shock when itachi activated MS

 

[Prime Rib]

i think so cause he noes itachi is a true heir of the sharingan