EasyExpat's guide to Brussels offers lots of advice to expats, including some info on sports:
"You can also find all the details of sport centers, leisure centers and federations where to practive your favorite sport on the Adeps' website (Administration de l'Education Physique et des Sports)." http://www2.adeps.cfwb.be/index.asp - hope that helps!

 

Let me know if you find a club to join, or want to have a hit when you arrive in Brussels. There are quite a few courts around but I haven't found much useful information about social comps.

 

Hi, I am looking for someone to play tennis with in Brussels... I am a decent player and I used to play tennis during my studies... Let me know if interested !