Maria Sharapova, right, congratulates Serena Williams on winning their women's singles final at the Madrid Masters on May 12, 2013. Javier Sorano / AFPA
Maria Sharapova, right, congratulates Serena Williams on winning their women's singles final at the Madrid Masters on May 12, 2013. Javier Sorano / AFPA
Serena Williams reigns on court, but Maria Sharapova has the edge in endorsements
According to Forbes magazine's annual list of the 100 highest-paid athletes, Serena Williams has the lowest endorsement portfolio among the six tennis players on that roll.