Originally posted by: Necromas
Originally posted by: XanBcoo
He was referring to Mangekyou Sharingan. Now, I have not read the manga, but I was under the impression that Itachi found out about Kakashi's Mangekyou at the same time we did - that is, very recently.

There is no way he could have known Kakashi was the third person nearly 10 years prior. He was referring to someone else, making Kakashi the 4th user.
Um are you stupid? He simply said Kakshi COULD get the mangekyou not that he already had one, if he was saying that, he'd also be implying that Sasuke already had one.
I'm pretty sure Itachi never said "Kakashi is capable of awakening the Mangekyou Sharingan within." or some anything similar to that. Yes, he said it to Sasuke, but I don't remember Itachi saying Kakashi is one of the three.

EDIT: After rewatching the episode, Itachi says in episode 131, at about 9 minutes in, that if Sasuke awakens the Mangekyou Sharingan within him, there will be 3 inluding Itachi who have ever used it.

Itachi doesn't mention who the 3rd is... So... It's not 100% correct that Kakashi is the 3rd.