She is the number 63 out of the 100.

The lack of female representation comes at a time when the issue of gender pay inequity in professional sports has gained attention and female players are willing to sue to put a spotlight on the disparity.

Williams, 37, reappeared on the list after Forbes calculated her pay at $29.2 million, as well as her winnings at $4.2 million and off-the-court endorsement deals at $25 million. Her sponsorships include Gatorade, Wilson Sporting Goods and JPMorgan Chase. She was also the only woman on the list in 2017.

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Number one on the list is Argentine soccer star Lionel Messi, whose pay, winnings and endorsement earnings reached a total $254 million. The second and third spot is also taken by footballers - Cristiano Ronald and Neymar jnr. respectively.

Four other tennis players made the ranking, including Switzerland's Roger Federer, who reached No. 5 and earned a total of $186.8 million.

In general, the top athletes represent major sports in the United States and internationally: soccer, football, basketball and baseball. Mike Trout, the Los Angeles Angels center fielder who earlier this year reportedly signed what appeared to be the largest contract in professional sports history worth $430 million over 12 years, was No. 17 on this year's Forbes ranking.