First, the problem:
Organizing Tennis matches is tedious.
Club level tennis players often spend a lot of time trying to set up a tennis match.
The player first needs to call the club to check for court availability. If she is lucky enough to find an available court she still have to call one of her friends and invite him or her to play.
She can be lucky again and her first pick could be available, or she will have to keep calling each one of her friends to find a rival.
This tedious task has become a little less tedious with the use of group chats, but it's still something that makes the player waste a lot of time, specially if she plays several times a week.