Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_27573848_18 (mountains_classification VARCHAR, winner VARCHAR)

### Question ###
If the winner is Rui Costa, who made the mountains classification?

### Accurate SQL ###

SELECT mountains_classification FROM table_27573848_18 WHERE winner = "Rui Costa"