Narrowing the Field: Sudden Death Elimination!

is episode 38 of the original Naruto anime.

Synopsis
Hayate reveals that an unusually large number of Genin passed the second stage of the exam. Before they can proceed to the final stage, a series of one-on-one preliminary matches will have to take place so that only the winners of each match can proceed. Kabuto drops out immediately upon the notice, blaming his withdrawal on an injury sustained from an earlier part of the test; however, he worries to himself that if he participated, the "old Kabuto might come out." The preliminary matches begin with Sasuke Uchiha versus Yoroi Akadō.