In episode 132 of Naruto, in the middle of the fight between Naruto and Sasuke, there is a flashback in which Itachi asks Sasuke to obtain Mangekyou Sharingan, and if he is able to obtain it, he will be the third guy to use it.
Who were the first and second persons, as both of his father and Tobi had Mangekyou Sharingan and he himself was using Mangekyou Sharingan?