CREATE TABLE table_68459 ("Outcome" TEXT, "Date" TEXT, "Surface" TEXT, "Opponent" TEXT, "Score" TEXT)

What was the surface of the match against bethanie mattek-sands?
SELECT "Surface" FROM table_68459 WHERE "Opponent" = 'bethanie mattek-sands'
SELECT "Surface" FROM "table_68459" WHERE "Opponent" = 'bethanie mattek-sands'