Usain Bolt & Asafa Powell sparkle in Diamond League 100m

BBC Sport looks back at this season's Diamond League 100m showdowns, where Jamaicans Usain Bolt and Asafa Powell plus Americans Justin Gatlin and Tyson Gay have battled for supremacy.

The seventh Diamond League meeting of the season takes place in London on Friday and once again all eyes will be on the sprinters, with Tyson Gay set to take on Britain's Dwain Chambers, while Powell is sidelined due to a groin injury.

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