Naruto: Shippuden Season 2 Episode 20 : The Power of Uchiha
Sasuke begins to attack Naruto, but Sai restrains him only for them both to be blown away by Sasuke's Chidori Nagashi. Sakura charges at Sasuke, but Yamato intervenes and winds up being stabbed by Sasuke's unique blade infused with his Chidori. The Nine-Tailed Fox tempts Naruto with its power, but he refuses it. Sasuke sees this using his Sharingan, appearing in Naruto's mind. The Nine-Tails says that Sasuke's chakra reminds him of Madara Uchiha, then Sasuke suppresses the Nine-Tailed Fox's chakra. Before the Nine-Tailed Fox returns to its cage, it warns Sasuke not to kill Naruto, saying that he will live to regret it forever.