Ranking the top 100 professional athletes since 2000 - ESPN

The greatest athlete of the 21st century? That's easy. It has to be Tom Brady, the quarterback of the greatest dynasty America's favorite sport has ever seen, a seven-time Super Bowl champ and five-time Super Bowl MVP. Yep. Tom Brady.

Except. Except it has to be Lionel Messi, the best player in the world's favorite sport, an eight-time Ballon d'Or winner as the footballer of the year. Yep, definitely Messi.

Except… no… LeBron James, right? Four-time NBA champ, four-time Finals MVP, four-time regular-season MVP, 20-time All-NBA, most points scored in NBA history. No athlete has dominated the public conversation like LeBron has. He has to be No. 1.

Except, what about Serena Williams? Winner of 23 Grand Slam titles, the Serena Slam (holding all four major titles at the same time) and four Olympic gold medals. And she got her final Grand Slam event win while pregnant, putting her career on hold while she was at her most dominant.

Except, if you are going to pick a tennis player, what about Roger Federer? He transformed an entire sport with his artistry, his chess game on the court, his blazing forehand. He won 20 Grand Slam titles and became the most beloved tennis player of all time. Gotta be Fed.

Yeah, except Rafael Nadal won 22 Grand Slam titles and Novak Djokovic has won 24. You have to pick one of them over Federer.

Hmm. Maybe this isn't so easy. We didn't even mention the Olympians: Usain Bolt and Michael Phelps and Katie Ledecky and Simone Biles. Or Kobe. Gotta throw Kobe Bryant into the discussion. Or Lewis Hamilton. Or Peyton Manning. Or Floyd Mayweather. Or Tiger. Geez, almost forgot about Tiger Woods.

Yes, ranking the top 100 most accomplished athletes since 2000 wasn't quite so easy after all — but it sure was