What was the surface for the opponent Roger Federer?
CREATE TABLE table_name_94 (surface VARCHAR, opponent VARCHAR)
SELECT surface FROM table_name_94 WHERE opponent = "roger federer"
### Context: CREATE TABLE table_name_94 (surface VARCHAR, opponent VARCHAR) ### Question: What was the surface for the opponent Roger Federer? ### Answer: SELECT surface FROM table_name_94 WHERE opponent = "roger federer"