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_8 (surface VARCHAR, opponent_s_ VARCHAR)

### Question ###
Which Surface has an Opponent(s) of anna-lena grönefeld tatjana malek?

### Accurate SQL ###

SELECT surface FROM table_name_8 WHERE opponent_s_ = "anna-lena grönefeld tatjana malek"