Tiger Woods is the top-earning American athlete according to SI's fourth annual rankings of the top 50, but he can't stay king forever. Here's a rundown of who SI thinks will one day make their way to the ranks of the top 50 earners.

No, he's not Peyton but he's only 26 and plays in the biggest media market in the nation. Do the Giants believe in him? The team exercised a buy-back of Manning's contract to keep him from becoming a free agent at the end of 2007. That made Manning $8 million richer. His salary increases to $8.45 million in 2008 and $8.95 million in 2009.