CREATE TABLE table_56733 ("Edition" FLOAT, "Zone" TEXT, "Round" TEXT, "Date" TEXT, "Against" TEXT, "Surface" TEXT, "Partner" TEXT, "Opponents" TEXT, "Result" TEXT)

What is the zone of the game played against Estonia?
SELECT "Zone" FROM table_56733 WHERE "Against" = 'estonia'
SELECT "Zone" FROM "table_56733" WHERE "Against" = 'estonia'