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_19 ( against VARCHAR, round VARCHAR, surface VARCHAR )

### Question ###
Who was the match against when on a clay surface during round 2r?

### Accurate SQL ###

SELECT against FROM table_name_19 WHERE round = "2r" AND surface = "clay"