Naruto vs the Uchiha is the thirteenth episode in Part IV.
Sensing Riyan's chakra near the village, Naruto arrives but is shocked to see Sasuke there too. He asks Sasuke why Koukon was meeting with Riyan, but Sasuke wouldn't answer him. Naruto turns his anger on Riyan and starts to form a Rasengan. Riyan laughs and declares that he isn't afraid of the Hokage. Sasuke remembers being the same way five years ago, before Naruto saved him. Even still, Sasuke also remembered his resentment for the village, and for it's people; the reason behind why he still refused to return, despite helping the village for Naruto's sake.
Naruto finishes forming the Rasengan and charges at Riyan, intending to kill him. Riyan then shocks Naruto by demonstrating his Sharingan's copy ability; copying Naruto's Rasengan and charging at him with one in hand. Sasuke suddenly appears and stops them both before telling Riyan he'll come with him, shocking Naruto and Ryun.