How do you get the announce in MK9 to say finish him, and then perform a finish him move?

OK so i start to fight lets say scorpion vs sub-zero, how do i get the opponent to dose off so i can perform a finish him move. like i keep pressing buttons on the ps3 and i kill the other guy. so the question is i do i get the announcer to say "finish Him" and then perform the finishing move