Picking up the manga story of chapter 176, Sasuke and Naruto are having their first official fight as rivals. Sasuke is taught two very painful lessons this episode, one by Naruto, and the other by Kakashi-sensei.
Naruto's rapid progress shows Sasuke that he's got a long way to go, thought to be fair, Sasuke has improved a great deal, but he was already considered to be an elite, Naruto's progress makes him feel like he's not gotten anywhere.
Kakashi reminds Sasuke that it's because he's got special people to protect, he has the Chidori. Both have suffered personal losses, but in spite of that, they still have prescious people in their lives.
Too bad this is the start of the Rescue Sasuke story arc, I'd have liked to have seen a bit more growth on Sasuke's part, before he takes the easy way out and joins Orochimaru.