CREATE TABLE table_name_57 (surface VARCHAR, round VARCHAR, player VARCHAR)

Which Surface has a Round of 4th round, and a Player of maria sharapova?
SELECT surface FROM table_name_57 WHERE round = "4th round" AND player = "maria sharapova"
SELECT "surface" FROM "table_name_57" WHERE "4th round" = "round" AND "maria sharapova" = "player"