The "specialized defensive player of the team". Plays defense only. Wears a diverse color of the uniform, in contrast to the rest of the group members. Controlled to carry out as a back row performer. Has no chance to deliver an attack (either from the back or front zones) when the ball is above the net. Is not permitted to serve, block or attempt to block. Substitutions involving libero are not recorded as usual substitutions and such are unlimited. Such is called "replacement". Can be replaced during dead ball only. An injured libero could be replaced regularly. The injured libero cannot re-enter the entire competition. Once a libero, (at the start), always a libero.