CREATE TABLE table_50843 ("Tie no" TEXT, "Home team" TEXT, "Score" TEXT, "Away team" TEXT, "Date" TEXT)

Who is the home team when Sheffield United is the away team?
SELECT "Home team" FROM table_50843 WHERE "Away team" = 'sheffield united'
SELECT "Home team" FROM "table_50843" WHERE "Away team" = 'sheffield united'