The Broken Seal

Naruto and Sasuke are both injured severely from Haku's Crystal Ice Mirrors before the latter reveals his Uchiha lineage by awakening his clan's own inherit ability: the Sharingan. With Sasuke's Sharingan allowing him to track Haku's incredibly fast movements, he is deemed a bigger threat than Naruto and a volley of senbon is used to force Sasuke to take a hit meant for his teammate. Believing his teammate had died in his arms, Naruto is enraged and unconsciously taps into the Nine-Tails' chakra to heal his wounds while attacking Haku.