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_16677887_2 (opponent VARCHAR, bills_first_downs VARCHAR)

### Question ###
What team were the bills playing where their first down was 23?

### Accurate SQL ###

SELECT opponent FROM table_16677887_2 WHERE bills_first_downs = 23