Rally!
In a volleyball game, a service specialist always had two tasks. First, it was to score a point from the service line. There was no explanation needed about this. However, if the first task couldn't be done, he had to ensure the second task was done, and that was to create chaos on the opponent's side. By doing that, it would scatter their formation and make their attack predictable.
'Listen, Hirano.' Akira said in the past. 'This is the cooperation that often happens between a service specialist like Yuki and a middle blocker like you. When Yuki was able to scatter the opponent's formation, you have to lock down their best player, because only the best player would be able to bring their team out of the chaos.'
Hirano remembered this instruction pretty vividly. That was why, whenever Yuki was on the service line, he was always ready for the opponent's best player. And that was why he was there, jumping to block Lucas's spike when the opponent was in chaos.