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_59 (round INTEGER, overall VARCHAR, position VARCHAR)

### Question ###
What is the lowest round for an offensive guard when the overall is smaller than 150?

### Accurate SQL ###

SELECT MIN(round) FROM table_name_59 WHERE overall < 150 AND position = "offensive guard"