opponent, adversary
He subestimado la fuerza de mi adversario.
I underestimated the strength of my adversary.
Él es un adversario formidable.
He is a formidable adversary.
He matado a muchos intentando encontrar un adversario digno.
I have killed many while trying to find a worthy adversary.
— Kung Fu Sion (2004)
Él será nuestro adversario, definitivamente.
He will definitely be our adversary.
— Toni Erdmann (2016)
Él sorprendió a su adversario.
He surprised his opponent.