The stadium isn't called "Газпром-Арена". Firstly, they thought, that stadium would be built by Gazprom and so the stadium, probably, would be called Gazprom-Arena. But stadium is constructed by the money of administration of Saint Petersburg. The current official name is "Футбольный стадион в западной части Крестовского острова" (Football stadium in the western part of Krestovsky island). We should use official name or, maybe, "Изградени стадиона за футболния клуб Зенит Санкт Петербург"
