I think Justine's game pretty much sum's up why I'm a fan
I first started watching tennis since Wimbledon of 2003. Back then, I only watched some matches from time to time, mainly of the Grand Slam types. Justine's matches always intrigued me. I love her attitude on court. Quiet, yet always calculating. I love that she's dedicated and such a fierce fighter. Of course, she's got an all-round great game and a killer backhand.
Since I started watching tennis so late, I never became a fan of Martina Hingis, although I am starting to really like her as well.