BBC Sport talks to American sprinter Tyson Gay about how it feels to beat Usain Bolt, and the sprinter also gives his reaction to his rival Asafa Powell's withdrawal from the upcoming Diamond League meeting in London because of injury.

Diamond League - London Grand Prix
Venue: Crystal Palace Dates: 13-14 August
Coverage: Watch Live on BBC 2 (Friday 1800-2100 BST), BBC 1 (Saturday 1300-1630 BST) and BBC Sport website (UK users only); full commentary on 5 live sports extra on Friday, updates on Radio 5 live on Saturday Full details