A total of 23 athletes at the first Youth Olympics in Singapore in 2010 went on win Olympic medals in 2012. Perhaps the most memorable was South African swimmer Chad le Clos, who beat Michael Phelps in the 200m butterfly.
Le Clos, now 22, was far more successful at the Youth Olympics, where he won five medals, including silver in the 200m fly.
“It taught me a lot of lessons that I wouldn’t have learned,” le Clos said. “A lot of people told me when I was younger that I wasn’t going to be a great butterfly swimmer. I shouldn’t even try to compete. Look at me a couple years later.”