Some people may have already read this, it is 3 years old but I just found this in wall street journal archive. WSJ actually had very good tennis coverage, especially around the bigger events.
http://online.wsj.com/article/SB124225824919117313.html
http://online.wsj.com/article/SB124225824919117313.html

Stuff in this article is really going to make me wonder during some of these lower ranked matches. I shall be contacting the Tennis Integrity Unit quite often over some of my losing wagers. lol