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

### Instruction:
Who was the opponent when there was 81 rushing yards?

### Inputs:
table_name: table, columns: ['Rank', 'Player', 'Year', 'Opponent', 'Passing yards', 'Rushing yards', 'Total offense']

### Response:
SELECT Opponent FROM table WHERE Rushing yards = 81