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_204_324 ( id number, "team 1" text, "agg." text, "team 2" text, "1st leg" text, "2nd leg" text )

### Question ###
who were the 6 teams to play in the first leg of the 2011 caf u-23 championship qualification ?

### Accurate SQL ###

SELECT "team 1", "team 2" FROM table_204_324 WHERE NOT "1st leg" IS NULL