Blake out of World Championships

Reigning 100 metres champion Yohan Blake has withdrawn from next month's World Championships because of a hamstring injury.

The 23-year-old Jamaican has been nursing the problem since April and did not compete in the national trials, but was an automatic qualifier for Moscow having won gold in Daegu in 2011 after team-mate Usain Bolt false-started in the final.

"This decision was made after continual assessment and re-evaluations since his withdrawal from the Jamaican Senior Championships," Blake's manager Cubie Seegobin said on skysports.com

"Yohan has made vast improvement, although the injury sustained in April of this year has prevented him from attaining the necessary fitness levels that we have grown accustomed to seeing in his competition performances."

Blake's withdrawal further weakens a 100m field which was already without Tyson Gay, the fastest man in the world this year, who tested positive for a banned substance, and Asafa Powell, who also returned a positive test but had not qualified anyway.