Sprinter Tyson Gay withdrew from the London Grand Prix yesterday, insisting the hamstring he injured at the US Olympic trials won't rule him out of next month's Beijing Games.

Gay was due to race against Jamaica's former world record-holder Asafa Powell in the 100 metres on Friday but said he wasn't taking any risks on the left leg.

"I was really looking forward to getting back on the track again, and training has been going well," said Gay, who was undergoing treatment in Germany. "I held out hope to run in London, but progress has been steady and with the first round of the Olympic 100 meters just three weeks away, I don't want to risk doing anything to set things back."

Doctors yesterday assessed Monday's MRI, which showed a mild strain in the semi tendinosus muscle, and said it was healing well.

"The decision does not affect Gay's plans for Beijing, by which time he is expected to be fully recovered," Gay's agent Mark Wetmore said.

Gay had already qualified for the 100m when he sprained a muscle in the back of his left leg in the 200m at the trials, a tumble that forced him to be carted off the track and ended his chances of winning two individual gold medals in Beijing.

He will also race in the Olympic 400-metres relay