CREATE TABLE table_21804557_18 (mountains_classification VARCHAR, metas_volantes_classification VARCHAR)

Who got the mountains classification when Michael Albasini won the stage?
SELECT mountains_classification FROM table_21804557_18 WHERE metas_volantes_classification = "Michael Albasini"
SELECT "mountains_classification" FROM "table_21804557_18" WHERE "Michael Albasini" = "metas_volantes_classification"