Usain Bolt: Can teen Yoshihide Kiryu match the Jamaican great?

“You are not getting the wins you once were to boost your confidence.”

The slender margins involved, and the physical power and unshakeable self-confidence required to be the best, make projecting senior 100m success from youthful promise a risky business.

Brown, the man whose time Kiryu matched in Hiroshima, is yet to improve on the silver medal he won as a 19-year-old in the senior 2003 World Championships.

British prospects Jason Gardener, Mark Lewis-Francis and Harry Aikines-Aryeetey all struggled to reproduce stellar junior results at senior level.

However, 2011 world champion Yohan Blake, double Olympic medallist Walter Dix and French national record-holder Christophe Lemaitre are some of the names among the junior stars who have gone on to greater things.

Reporter Kazushi Nagatsuka, who has covered Kiryu’s career for the Japan Times, fears his compatriot could fall into the former camp.

“Japanese athletes are competitive against anyone in the world when they are younger,” he told BBC Sport. “But as they get older, they falter and, in some sports, they can’t even compete – mainly because of their size.

“Maybe they get worn down as well because they train so hard. They are often at schools like boot camps.”

Certainly Kiryu is excelling in a discipline in which his country has not had much success.

His personal best of 10.01 was only one hundredth off Japan’s national 100m record set by Koji Ito in 1998 and two hundredths off the Asian record set by Nigerian-born Qatari Samuel Francis in 2007.

Internationally, Japanese sprinters rarely reach major finals, with Shingo Suetsugu’s 200m bronze medal in the 2003 World Championships a rare podium finish.