Sasuke is severely hindered by the Curse Mark placed on him by Orochimaru, which drains his chakra and prevents him from using Ninjutsu. Yoroi exploits this by using a chakra-absorbing technique.
Sasuke Uchiha faces off against Yoroi Akado, a minion of Orochimaru. Naruto (Dub) Episode 39
). He successfully defeats Yoroi without activating the Curse Mark, moving on to the next round. Sasuke is severely hindered by the Curse Mark