Episode: Naruto Shippuuden - 487 - Sasuke`s Story: Sunrise, Part 4 - The Ketsuryugan ic12

Sasuke uncovers Fuushin’s true identity at last, and begins to fight him. The moment Sasuke tries to read Fuushin’s memories with his Sharingan, a wave of genjutsu from a massive red eye causes Sasuke to lose consciousness. He awakens to find himself alone, and sees tracks in the snow that indicate Fuushin has barely escaped alive.

Source: crunchyroll