Kakashi: Sharingan Warrior!

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 and look into the future with his Sharingan, and used the many water jutsu that Zabuza knew. Kakashi's water jutsu eventually threw Zabuza into a tree, and Kakashi prepared to finish him off, but the former was "murdered" by a hunter-nin from the Hidden Mist Village.

Secretly, the hunter-nin was an apprentice of Zabuza, and had faked his death.