Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### 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"