Who is the greatest tennis player of all time?
In the modern era and based on total titles and the overall impact on the game, both Serena Williams and Roger Federer as considered the greatest player of this generation
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: Who is the greatest tennis player of all time?
### Input: 
### Response: In the modern era and based on total titles and the overall impact on the game, both Serena Williams and Roger Federer as considered the greatest player of this generation