On what surface did they play the match in the week of October 21?
CREATE TABLE table_name_27 (surface VARCHAR, week VARCHAR)
SELECT surface FROM table_name_27 WHERE week = "october 21"
### Context: CREATE TABLE table_name_27 (surface VARCHAR, week VARCHAR) ### Question: On what surface did they play the match in the week of October 21? ### Answer: SELECT surface FROM table_name_27 WHERE week = "october 21"