user: ### NOW ANSWER:
Question: Which Against has a Round of Fourth round?
Columns: ['Opposing Team', 'Against', 'Date', 'Venue', 'Round']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['Ipswich Town', 0.0, '05/01/2008', 'Portman Road , Ipswich', 'Third round']
SQL:

assistant: SELECT MIN("Against") FROM "Table" WHERE "Round" = 'Fourth round';