Boruto and the others get a shock when the organizers of the Chunin exam announce the final round. Naruto, Sai, and Shikamaru want to make this round as difficult as possible for the genins. Most importantly they want to see how well the genins adapt to various situations.
To make things more interesting, a participant’s opponent would not be announced until the day of the test. As stressful as that may sound, there is still a silver lining. The genins are granted a rest day where they can use their time to train if they so desire.