Harry Wombat
Did you serve something privately and are waiting to see if those served want to take the matter/matters public?
My guess is that you served them so well privately, and provided so many courtesies that they are afraid of your tennis skills and don't want to be humiliated in a public game of tennis.
I'm also guessing they know you have the EVIDENCE to show that you won every match against them so far.
:)