World record holder Paula Radcliffe will not be able to attempt to claim her fourth Flora London Marathon title next month after sustaining a toe tendon injury at her training base in the United States.
Radcliffe's injury comes just five months before she bids for the Olympic title in Beijing where she is determined to atone for dropping out of the 2004 race.
But she is determined to be fit again for the tough task awaiting her in the Chinese capital.
The 34-year-old sustained the injury to her right toe while altitude training at her base in Albuquerque, New Mexico and in mid-February returned to Europe for specialist treatment.
Radcliffe won the London title in 2002, 2003 and 2005 and said: "I am desperately disappointed that I have to pull out of this year's race.
"I love running in London and this race would have been the perfect test for me before the Olympic Games.
"But in marathon training there are no short cuts and there is simply not enough time to be in the shape I want to be in to run well in London.
"Now I must concentrate on being as well prepared as possible for Beijing."
Radcliffe admits the injury is a blow to her plans but she still believes she can be in excellent condition for the Olympic marathon on 15 August.
London Marathon race director David Bedford said: "Of course, it is a major blow to lose Paula from this year's race but we understand that her priority in 2008 is to be in peak condition for the Olympic Games and we wish her all the best for a speedy return to full fitness.
Bedford insisted: "Even without Paula we will still have a very strong international women's field on 13 April and I am sure the race will be as exciting as ever."Reuse content