Naruto Shippuden Episode 42

Title: "Orochimaru VS Jinchūriki"
Date: January 10, 2008

Naruto, in the four-tailed state, begins attacking Orochimaru with incredible force, devastating the surrounding landscape and preventing Sai and Yamato's wood clone from approaching him. The majority of Orochimaru's attacks prove to be ineffective, but Naruto also fails to kill Orochimaru as he regenerates from any injuries he sustains. Meanwhile, Kabuto advances toward Sakura and Yamato, deducing that Sasori has died. Orochimaru finally manages to strike Naruto with a sword blade from his mouth, and Sakura reacts in horror when she sees Naruto's four-tailed state.