Some of the leading lights on the WTA Tour have dipped spectacularly over the past few months, providing an intriguing shake-up at the top of women's tennis.
Victoria Azarenka is the latest star trying to emerge as a genuine force, as highlighted by her superb victory in the Sony Ericsson Open at Key Biscayne.
Jankovic's dramatic slump is such that she fails to make the Yahoo! Sports top eight, as we take a look at the most dangerous players on the circuit - regardless of what the rankings computer says.
1. Serena Williams: Injured in Miami but still the best player on tour
2. Venus Williams: Only lost once since the Australian Open - to her sister
3. Vera Zvonareva: Putting together a breakthrough year
4. Victoria Azarenka: Red-hot rising star dominated in Miami
5. Caroline Wozniacki: Fast-climbing Danish teenager is a class act
6. Dinara Safina: Looking forward to clay court season after two bad months
7. Elena Dementieva: Disappointed in North America with back-to-back upsets
8. Ana Ivanovic: Indian Wells final can't mask drastic decline