CREATE TABLE table_51661 ("Edition" CLOB, "Round" CLOB, "Date" CLOB, "Surface" CLOB, "Opponent" CLOB, "Result" CLOB)

What surface was the April 24, 2003 match played on?
SELECT "Surface" FROM table_51661 WHERE "Date" = 'april 24, 2003'
SELECT "Surface" FROM "table_51661" WHERE "Date" = 'april 24, 2003'