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).