Jamaica sprinter Asafa Powell believes drug testing has taken so much of his b****0d at the Beijing Olympics that it could hamper his 100m final run.

Former world record-holder Powell, who could be checked again on Wednesday, said the tests on himself and his team-mates at the Games had gone too far.

"They've tested me four times here; they're taking so much  b****0d I'll be weak for the final," Powell said.

Beijing aims to be dope-free with extra checks being used to avoid drug cheats.

"I'm almost sure I might be tested again. I don't know about anyone else but they're really doing it in my case and with my team-mates Michael Frater and Usain Bolt," he added.

"They're saying they're doing about 4000 tests. It's just very difficult to catch everyone but I hope they can do it and make this Olympics clean."

Athletes in China will be the most tested in history because of the stringent measures, with authorities paying particular attention to the sprinters after recent doping revelations.

Athens' winner Justin Gatlin of the US is currently serving a four-year ban for doping offences.

Compatriot Tim Montgomery, a winner in the 4x100m relay in Sydney, was a client of BALCO, the San Francisco laboratory which produced the designer steroid THG.