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_20946 ( "Round" real, "Circuit" text, "Date" text, "Pole Position" text, "Fastest Lap" text, "Winning Driver" text, "Winning Team" text )

### Question ###
Who had the fastest lap in the race won by Team Impul at the Twin Ring Motegi circuit?

### Accurate SQL ###

SELECT "Fastest Lap" FROM table_20946 WHERE "Winning Team" = 'Team Impul' AND "Circuit" = 'Twin Ring Motegi'