The inclusion of the figure of the "libero" was done to try to increase the teams’ defensive potential. The objective of the present study was to analyze the association between the player that intervened in defense (libero or other player), the defensive efficacy and the counter-attack performance. A total of 960 defensive actions were analyzed in 33 sets of the classificatory and final phases of the World League in 2004. The variables studied were: player that intervened in defense (libero or other player); zone of defense intervention; zone where counter-attack was made; tempo of the spike; defensive efficacy; distribution efficacy; and counter-attack efficacy. The likelihood that the spikers used the second tempo in the counter-attack phase was greater when the libero defended. Likewise, the likelihood of an excellent defense occurring, which allows the team all its attack options, increased when the libero executed the defense. There is no association between the player that intervened in defense (libero or other player) and zone of attack, number of blockers that the hitters oppose in counter-attack, and counter-attack efficacy. In summary, the intervention of the libero is associated with better efficacy in defense and with quick attacks (second tempo). However, the intervention of the libero is not associated with an improvement of the counter-attack performance of its team.