606.7a.

Each team's creatures attack the other team as a group. During the combat phase, the active team is the attacking team and each player on the active team is an attacking player. Likewise, the nonactive team is the defending team and each player on the nonactive team is a defending player. Any one-shot effect or characteristic-setting ability that refers to the "defending player" refers to one specific defending player, not to both of the defending players. The controller of the effect or of the object with the characteristic-setting ability chooses which one the spell or ability refers to. The same is true for any one-shot effect that refers to the "attacking player."