In an effort to get stronger, Naruto trains harder than Sasuke and Sakura. Though he catches up to both in terms of talent, exerting the extra effort leaves him fatigued. To allow him a chance to regain his energy, the rest of Team 7 goes on to escort Tazuna without him. Soon afterwards, however, they are attacked again by Zabuza and a masked Haku. Using his new training, Sasuke does battle with Haku and proves to be an equal match, forcing Haku to trap him in a prison of ice. Naruto quickly arrives to help and joins Sasuke in the fight, though both are soon overpowered. As Haku makes to finish Naruto off, Sasuke uses himself as a shield to block the attack and appears to be killed. Naruto, in his anger, taps into the dormant powers of the demon fox sealed within him.