CREATE TABLE table_57611 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What was the opponent of the home team of essendon?
SELECT "Away team" FROM table_57611 WHERE "Home team" = 'essendon'
SELECT "Away team" FROM "table_57611" WHERE "Home team" = 'essendon'