Floyd Mayweather Jr.'s two fights this year will earn him an estimated… (Al Bello / Getty Images )
Floyd Mayweather Jr. has lived up to his nickname again in 2013.
The boxer known as "Money" has made lots and lots of it -- an estimated $90 million -- so far this year. That's way more than any other athlete in the U.S., or the entire world for that matter.
For the second year in a row, Mayweather tops Sports Illustrated's list of the highest-earning American athletes. The rankings use estimates that combine salary, winnings and endorsements -- although Mayweather's earnings come solely from his fight with Robert Guerrero earlier this month and his upcoming September bout with Saul "Canelo" Alvarez.
Miami Heat star LeBron James is No. 2 with estimated earnings of $56 million, followed by New Orleans Saints quarterback Drew Brees ($47.8 million), the Lakers' Kobe Bryant ($46.9 million) and golfer Tiger Woods ($40.8 million).
Former Galaxy star David Beckham tops the magazine's international list at $48.3 million, almost all of which comes from endorsements.
Tennis standout Roger Federer dropped to No. 2 ($43.4 million) after four years atop the international ranking. He's followed by Formula 1 racer Fernando Alonso ($42 million) and soccer stars Cristiano Ronaldo ($35.3 million) and Lionel Messi ($35.1 million).
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