CREATE TABLE table_25957 ("Edition" TEXT, "Round" TEXT, "Date" TEXT, "Against" TEXT, "Surface" TEXT, "Opponent" TEXT, "Result" TEXT, "Outcome" TEXT)

If the date is 7-21-2006, who was the opponent?
SELECT "Opponent" FROM table_25957 WHERE "Date" = '7-21-2006'
SELECT "Opponent" FROM "table_25957" WHERE "Date" = '7-21-2006'