I think for this, it could be a month or so long event, like Mahunoshiro, where you can teleport to the event to do quests, as Yusuf suggested. You could then get collectables from an NPC, etc. Then, for the main event, there could be a class (Like how the Winter Waltz worked) that takes you to the actual World Cup game. Then, the Dark Followers would attack for the main event.