Usain Bolt, Asafa Powell and Tyson Gay, all sub-9.8 second performers, seek sprinting's ultimate validation in a 100 metres showdown that will be the highlight of the athletics programme at the Beijing Olympics.

Despite being badly tainted by the doping revelations that felled the men's winner from four years ago and the 2000 women's champion Marion Jones, the sport's blue riband race remains the most magnetic event of the Games.

The men's 100 metres in Athens four years ago was a classic, with the first five men breaking 10 seconds for the first time. Jamaican Powell came in fifth in 9.94 behind winner Justin Gatlin of the United States, who was later banned for doping.

A year later, on the same track, Powell set a world record of 9.77 and improved it to 9.74 in 2007.

Compatriot Bolt moved the mark on to 9.72 this year while Gay posted 9.77 plus a wind-assisted 9.68, the fastest time recorded for the distance.

All three are capable of taking gold and the world record with it in the final on Aug 16.

Powell was favourite in the world championships a year ago but managed only bronze behind winner Gay. It was a performance that raised questions over the Jamaican's temperament after he admitted giving up once he realised he would not win.

Injuries have limited his work this year and Gay also suffering a hamstring problem in the US trials that ended his hopes of making the 200 metres team.

'This year for the first time all eyes will be on Bolt and Gay. Definitely after the disappointments of recent years when I was favourite, I prefer this sort of situation,' Powell said.

Bolt's progress in the 100 metres was a surprise for a man better known for the 200, in which he took silver behind Gay in the world championships.

Clearly the fastest over 200 this season, the 21-year-old will hope to prevent a repeat of the U.S. clean sweep of 2004.