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

### Instruction:
At the 2001 Davis Cup, what Opponent had less than 50 Aces?

### Inputs:
table_name: table, columns: ['Aces', 'Player', 'Opponent', 'Event', 'Sets']

### Response:
SELECT Opponent FROM table WHERE Aces < 50 AND Event = 2001 davis cup