What does romeo fear in act 1 scene 4?

Romeo fears being discovered by Tybalt in Act 1, Scene 4. Tybalt is a member of the Capulet family, and he is known for his fiery temper and hatred for the Montagues, Romeo's family. Romeo knows that if Tybalt finds him at the Capulet ball, he will likely challenge him to a fight, which could have deadly consequences.