It looks like they get to practice a song of their own choosing. Then each team gets called on the stage where the coach picks a pair to battle against each other. I would have prefer that the audience decides who moves on or to make the coaches vote. The coach's vote of the pair battling counts as 2 to avoid a tie or the audience vote will break the tie.
I found one spoiler about the knockout rounds. If it is true,Click to see Spoiler:about Blake's team, then Terry does NOT make it. I had a bad feeling when I watched the preview. I hope it is wrong and just trolling