String Fiddlers - Who Waits For Who?

Question:

My opponent often fixes his strings as I’m preparing to serve.
This makes a distracting noise, and he does this through my service delivery. I know he’s not doing it intentionally—he said it’s more of a nervous habit—but am I allowed to ask him to stop?—Jeremy from Sheffield.

Answer:

You don’t need to ask—just don’t serve.
Rule 21 says the server “shall not serve until the receiver is ready.” Someone fiddling with his racquet strings isn’t ready. Wait him out. And in theory, if you’re ready to serve, the receiver has to play to your “reasonable pace” and could be penalized under the same rule for the delay if the fiddling continues.

But that would take an official at the court.