Hey! How're you doing?
I'm very comfortable writing about tennis as I've been playing tennis for 9 years and I know everything about it. Unfortunately, tennis season is currently closed and will re-open on January 1st, 2013, for this reason I can write on winter sports (mostly biathlon and curling, I'm pretty good at it) until new tennis season is re-opened.
I usually charge $1 per 100 words, but I'm ready to make you a Christmas present and discount a price to $0.75 per 100 words since it is not really difficult to write about sports.
I had my own blog about tennis (link sent in private message), but I closed it the day season was ended in 2012.
Shoot me a message if you are interested.
Yours truly,
Sebastian