Forbes.com reported Wednesday the quartet is Maria Sharapova of Russia ($26 million), American sisters Serena and Venus Williams ($14 million and $13 million respectively) and recently retired tennis player Justine Henin of Belgium ($12.5 million).

"The tour has a much more international flavor to it," said David Carter of the Sports Business Group, an industry consultant. "The chance does exist, especially as women's sports get more coverage in the Olympics," Carter added when discussing the issue of whether women's team-sport athletes ever catch up to men in earnings.

Golfer Michelle Wie of Hawaii is No. 5 despite a failure to win a tournament and two disqualifications on the LPGA Tour after a much-publicized start to her career.

Spots 6-10 are filled by golfers Annika Sorenstam ($11 million) and Lorena Ochoa ($10 million), IndyCar driver Danica Patrick ($7 million) and tennis' Ana Ivanovic ($6.5 million).