The Kansas City Chiefs have agreed to a 10-year contract extension with quarterback Patrick Mahomes that is worth $503 million, making him "the first half billion dollar player in sports history," his agency tweeted. The Super Bowl MVP's contract is the richest-ever not just at the NFL but in all of professional sports, the AP reports, surpassing Mike Trout's $426.5 million deal with the Los Angeles Angels. The Chiefs won their first Super Bowl in 50 years this February, with the 24-year-old QB helping his team come from behind in the second half, per NBC News. "The best part is he's still early in his career," the team's head coach, Andy Reid, said in a statement confirming the deal. "He's a natural leader and always grinding, whether that's on the field, in the weight room or watching film, he wants to be the best." (More Patrick Mahomes stories.)