CREATE TABLE table_33876 ("Player" CLOB, "Ranking" CLOB, "Event" CLOB, "Surface" CLOB, "Round" CLOB, "Score" CLOB)

Which Surface has a Round of 4th round, and a Player of maria sharapova?
SELECT "Surface" FROM table_33876 WHERE "Round" = '4th round' AND "Player" = 'maria sharapova'
SELECT "Surface" FROM "table_33876" WHERE "Player" = 'maria sharapova' AND "Round" = '4th round'