Opponent of at san francisco 49ers had what lowest week?
CREATE TABLE table_name_43 (week INTEGER, opponent VARCHAR)
SELECT MIN(week) FROM table_name_43 WHERE opponent = "at san francisco 49ers"
### Context: CREATE TABLE table_name_43 (week INTEGER, opponent VARCHAR) ### Question: Opponent of at san francisco 49ers had what lowest week? ### Answer: SELECT MIN(week) FROM table_name_43 WHERE opponent = "at san francisco 49ers"