One has acquired more Olympic medals than any other athlete in history. The other was knocked out of the Games after just 250 seconds. But Michael Phelps and Ashley McKenzie, the 23-year-old British No 1 judoka, have one thing in common: both have attention deficit hyperactivity disorder (ADHD), as does another high-profile Olympian, British gymnast Louis Smith, who this week helped win the first British men's gymnastics team medal for a century.
Suddenly, a condition that is hugely stigmatised and still controversial, is unexpectedly in the spotlight. It raises several interesting questions. Does ADHD hinder or help sporting success? And can the Olympics offer a positive legacy for people suffering from it?