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_18143210_2 ( first_season_in_top_division VARCHAR, club VARCHAR )

### Question ###
When did the club UNAM played the first season in top division?

### Accurate SQL ###

SELECT first_season_in_top_division FROM table_18143210_2 WHERE club = "UNAM"