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_name_23 (rank__number VARCHAR, opponent_number VARCHAR)

### Question ###
What was the rank when the opponent was Wisconsin (played at Wisconsin)?

### Accurate SQL ###

SELECT rank__number FROM table_name_23 WHERE opponent_number = "at wisconsin"