Injured Asafa Powell pulls out of London Diamond League

Powell (left) had no answer to Bolt (far right) at the 2009 World Championships in Berlin

Asafa Powell has pulled out of Friday's Diamond League meeting in London because of a groin strain.

The former world record holder was due to run in the 100m at Crystal Palace, the final main event before the World Championships begin on 27 August.

Fellow Jamaican Yohan Blake heads the field in Powell's absence.

Powell, the fastest man in the world this year, will go head-to-head with compatriot Usain Bolt at the Championships in Daegu, South Korea.

He said: "I've had some tightness in my groin since (competing in) Budapest.

"I had hoped that it would have cleared by now but it's still there. I've been seeking treatment but had to make the decision to withdraw.

"I am focusing on Daegu and as much as I'd like to run, I just can't take the risk with the major championships three weeks away."

Powell believes Bolt may not be as dominant because of a back injury which has disrupted his preparations in 2011.

"It's hard to get everything flowing, he's had problems getting his rhythm back," Powell told BBC Sportsworld.

"I know how to come back from injuries and I'm better technically."

Bolt was suffering from back problems and would not run again for the rest of 2010.

Despite Powell's verdict, 24-year-old Bolt has captured all the major honours, winning 100m, 200m and 4x100m relay golds at the 2008 Beijing Olympics and 2009 World Championships in Berlin.

In addition to his triple gold medal haul in Berlin he set top 200m time of 19.19secs.

This year, however, Powell is currently the fastest man in the world with 9.78secs set in Lausanne on 30 June while Bolt, who is not racing this week in London, has a best of 9.88secs, recorded in Monaco on 22 July.

Twice a bronze medallist at the World Championships, Powell says he wants to "make sure I achieve what I feel like I deserve" by claiming gold this year in Daegu.

"I'm not going to waste my chance again," the 28-year-old added.