Kakashi: Sharingan Warrior! (写輪眼のカカシ, Sharingan no Kakashi) is episode 9 of the original Naruto anime.

Synopsis

With his teamwork with Sasuke, Naruto's strategy was shown unfolding. Zabuza was tricked into breaking his hold on Kakashi to avoid certain death. After Kakashi was saved from Zabuza's Water Prison Technique, he attacked Zabuza with multiple water techniques. He also seemed to copy using his Sharingan, as the Sharingan allows its user to copy techniques to minutest detail thus allowing him to use Zabuza's techniques against him. Kakashi's water technique eventually threw Zabuza into a tree, and Kakashi prepared to finish him off, but the latter was "murdered" by a hunter-nin from the Kirigakure. Kakashi then collapsed from exhaustion due to the overuse of his Sharingan after the battle was over.