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_45861 ( "Outcome" text, "Year" real, "Championship" text, "Surface" text, "Partner" text, "Opponents in the final" text, "Score in the final" text )

### Question ###
What was the surface played on when they were a runner-up in 2007?

### Accurate SQL ###

SELECT "Surface" FROM table_45861 WHERE "Outcome" = 'runner-up' AND "Year" = '2007'