The Voice (TV series)
In the battles, coaches decide to pair two artists from their team against each other, performing the same song in a "boxing ring" type arena.  The paired artists train together with their coach to improve upon their skills.  Each sings a different parts of a song, relay style. The artists perform at the same time in the battles. Once the song is over and the coaches make their comments, it is up to the contestant's coach to decide who is the winner of the battle. The winner advances to the knockouts. Coaches have saves and steals which they can use to save an artist on their team, or steal one from another team. However, these are limited.