Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Lowest against for tour match on 21 july 1990?

### Inputs:
table_name: table, columns: ['Opposing Team', 'Against', 'Date', 'Venue', 'Status']

### Response:
SELECT MIN Against FROM table WHERE Status = tour match AND Date = 21 july 1990