CREATE TABLE table_75867 ("Round" CLOB, "Opposition" CLOB, "First leg" CLOB, "Second leg" CLOB, "Aggregate score" CLOB)

Who were the opposition in the quarter-final?
SELECT "Opposition" FROM table_75867 WHERE "Round" = 'quarter-final'
SELECT "Opposition" FROM "table_75867" WHERE "Round" = 'quarter-final'