CREATE TABLE table_38066 ("Outcome" CLOB, "Year" FLOAT, "Championship" CLOB, "Surface" CLOB, "Opponent" CLOB, "Score" CLOB)

Which championship has Roger Federer as an opponent on a clay surface in a year earlier than 2007?
SELECT "Championship" FROM table_38066 WHERE "Opponent" = 'roger federer' AND "Surface" = 'clay' AND "Year" < '2007'
SELECT "Championship" FROM "table_38066" WHERE "Opponent" = 'roger federer' AND "Surface" = 'clay' AND "Year" < '2007'