My, how things have changed

It wasn't that long ago that:

• Serena Williams was the player to beat

• Maria Sharapova was a very bright star on the tour

• Kim Clijsters was headed toward a great 2011 season

• Jelena Jankovic was "a step away" from meeting her potential

• Sabine Lisicki appeared to be Germany's Next Big Thing

• Julia Goerges was a good-enough German player who showed some potential

• Ana Ivanovic looked like she was regaining her prestige

• Sam Stosur was heralded  on clay surfaces

Things have changed. Williams, a victim of especially nasty bad health luck, has been out for months and months. Clijsters has three injuries and may not play in the French Open. Sharapova is slowly getting her groove back, but fans are nervous. Stosur hasn't been the same since she lost the 2010 French Open to Francesca Schiavone.

Ivanovic, who can't even keep a coach in her employ, is lost somewhere in the tennis cosmos, and her countrywoman, Jankovic, has sadly misplaced her confidence. Lisicki, who was either sick or injured for months, is finally making a bit of a comeback, but she is still a shadow of the player who came out of nowhere and won Charleston in 2009. In the meantime, German player Andrea Petkovic has steadily increased both her skills and confidence, and has become a threat in many tournaments.

The most interesting German story, however, is that of Julia Goerges. Goerges has shown potential for a long time, with her strong hitting on both sides, but she broke through and won Stuttgart, beating world number 1 Caroline Wozniacki in the final. Then she beat her again in Madrid, and will play in the semifinals tomorrow. Sometimes people forget how important confidence is, and Goerges must be feeling a lot of it right now.

Consistency has been Wozniacki's strength, though she hasn't yet won a major, and her chance to do so may not come until the U.S. hard court season arrives.

Then there's Petra Kvitova--whom some of us have been watching for a long time. She sneaked into the 2011 season with two titles, then backed off a bit (there was an injury issue), but is making a surprising run on red clay in Madrid. Kvitova has semifinal points to defend at Wimbledon, and her chances of defending them are pretty good. More focused and careful than she used to be, Kvitova is mentally strong and probably has nowhere to go but up.

What about the other Russians? Elena Dementieva has retired, and the extraordinarily gifted Svetlana Kuznetsova has trouble winning. Dinara Safina was taken out of the tour by a serious back injury, and has not found her way since her return. Nadia Petrova has some health problems, but she has run hot and cold for a few years now. Anastasia Pavlyuchenkova keeps getting better, but it's Vera Zvonareva who has outshown them all. A two-time major finalist, Zvonareva has a lot to prove this year; she is now "the" Russian, and it's a bonus that she is intelligent and articulate (and can break a racquet with more panache than anyone in history). But despite Zvonareva and Pavlyuchenkova, the Russians no longer dominate.

Since we're talking about change, Ii's only natural that people would speculate about the Williams sisters' retirement. I think they will try to be around for the 2012 Olympic Games, but both of them now have health issues that make it hard for them to compete. Of course, it's the work of a fool to ever count out Serena Williams, so--like everyone else--I'm waiting to see what will happen.

Everything, by the way, could change again tomorrow--that's the nature of professional tennis. And if you doubut that, I have two words for you: Francesca Schiavone.