YOU SAID:

they have to do a final one

INTO JAPANESE

彼らは最終的なものをしなければなりません

BACK INTO ENGLISH

they have to do the final

INTO JAPANESE

彼らは決勝戦をしなければならない

BACK INTO ENGLISH

they have to play the final

INTO JAPANESE

彼らは決勝戦をしなければならない

BACK INTO ENGLISH

they have to play the final