Serena Williams has been so good for so long that it's easy to take her for granted, but that's a disservice to an all-time great who, at 31, keeps working harder and getting better.
Maria Sharapova's determination to overcome both her awkwardness on clay and major shoulder sugery paid off with a career-defining French Open title last year.
Sure, Victoria Azarenka only has one Grand Slam title to her credit, but the current No. 1 has proved she belongs among tennis' elite ranks.
The No. 1 ranking in women's tennis has become devalued as players have come and gone at the top spot. Can Serena restore order?