Tyson Gay (L), Usain Bolt(C) and Asafa Powell. [Agencies]

100m: Usain Bolt v Asafa Powell v Tyson Gay

Powell and Bolt are the past and present record holders in the event, while Gay ran even faster but was not counted because of the wind. There are doubts over all three of them, the two Jamaicans because of their big race temperament and Gay because of a left hamstring injury.

Dayron Robles and Liu Xiang. [Agencies]

110m hurdles: Liu Xiang v Dayron Robles

Liu Xiang, the reigning Olympic and world champion and former world record holder, carries China's great expectations on his shoulder.

Robles, who has set a new world record of 12.87sec, may benefit should Liu find the pressure unbearable.

LaShawn Merritt and Jeremy Wariner. [Agencies]

400m: Jeremy Wariner v LaShawn Merritt

Wariner saw his nine-race unbeaten streak ended by Merritt, and then lost out again in the US Olympic trials. But he has hit back with two successive wins over Merritt in Rome and Paris.

Angelo Taylor (L) and Bershawn Jackson (right). [Agencies]

400m hurdles: Angelo Taylor v Bershawn Jackson

Will it be another Taylor-made Olympic success eight years after he crossed the line first in Sydney or will his rival nicknamed 'Batman' get his man?

Jackson - who has already shown he has the big race temperament by winning the 2005 world title in Helsinki - clearly had the better of Taylor at the Olympic trials where the 25-year-old finished first.  

However, they will both be primed and ready for the greater challenge of an Olympics and provide a battle royale.