$23 million of Sharapova's income comes from her many endorsements. (Adrian Dennis/Getty Images)
Maria Sharapova tops Forbes' annual list of the highest-paid female athletes for the ninth consecutive year. Serena Williams, Li Na and Victoria Azarenka round out the top four, and tennis players occupy seven of the top nine spots overall.
Tennis' domination of the list, which measures an athlete's earnings through prize money, endorsements and appearance fees from June 2012 to June 2013, underscores the fact that the WTA is the premier women's sporting organization in the world. WTA players are generally offered compensation on par with the men at the sport's biggest tournaments. They are also afforded endorsement opportunities that are unrivaled in other sports.
Tennis stands in sharp contrast to other sports in how well the top men and women are compensated. As Forbes points out, South Korean golfer Inbee Park won $585,000 for her U.S. Open victory; men's champion Justin Rose earned more than twice that amount, $1.4 million. According to Forbes, the 10 highest-paid tennis players are now equally split between men and women. Only Roger Federer and Rafael Nadal pulled in more money last year than Sharapova.
When it comes to endorsement power, Sharapova tops the list with an astounding $23 million. Li is next, with $15 million in endorsements. Perhaps the most surprising revelation is that in a year in which she won two Grand Slam tournaments and an Olympic gold medal, Williams earned just $1 million more in endorsements than Wozniacki.
Here's how this year's Forbes list shakes out among tennis players:
1. Maria Sharapova - $29 million ($6 million in prize money), up $1.9 million from last year.
2. Serena Williams - $20.5 million ($8.5 million in prize money), up $4.2 million from last year.
3. Li Na - $18.2 million ($3.2 million in prize money), down $200,000 from last year.
4. Victoria Azarenka - $15.7 million ($6.7 million in prize money), up $6 million from last year.
7. Caroline Wozniacki - $13.6 million ($2.6 million in prize money), down $100,000 from last year.
8. Agnieszka Radwanska - $7.4 million ($4.9 million in prize money), up $500,000 from last year.
9. Ana Ivanovic - $7 million ($1 million in prize money), down $200,000 from last year.