Paula Radcliffe has pulled out of next week's Commonwealth Games in Melbourne because of a foot injury.
The 32-year-old world marathon champion suffered the injury in January after stepping on a rock and has not been able to prepare fully for the Games.
"We feel it would be stupid to compete in Melbourne," said Radcliffe's manager and husband Gary Lough.
Radcliffe won the 5,000m Commonwealth title in Manchester and was favourite to win the 10,000m in Australia.
She has been training for the Commonwealth Games as well as the London Marathon at the high-altitude venue of Albuquerque in New Mexico.
"The problem is not affecting her marathon preparations"
Although she has been able to continue with her marathon preparations, Radcliffe had difficulties with her track sessions - affecting her Melbourne build-up.
"Paula hit a rock when out training and developed a bruised foot and it is taking a long time to settle down," Lough added.
"In particular it has been causing problems on the track, constantly flaring up and she cannot do proper flat-out training sessions."
However, Lough insists the marathon world record-holder will be well prepared to defend her London Marathon title on 23 April.
"The problem is not affecting her marathon preparations," he added.
London Marathon race director David Bedford says Radcliffe will benefit from only having to focus on one event and believes the decision could help her to break her world record - the two hours 15 minutes and 25 seconds she set in 2003.
"Along with the rest of the country, I'm disappointed she will not be running at the Commonwealth Games.
"Perhaps at the same time, this will help her preparations for the Flora London Marathon," he said.
"I definitely believe she can go much faster. She is capable of running under two hours 15 minutes - but it is a question whether she can run sub 2.14."
Radcliffe missed the 1994 Commonwealth Games in Canada with a stress fracture while a virus forced her to pull out of the Kuala Lumpur Games in 1998.
Ann Hogbin, England team boss at the Commonwealth Games, said: "Naturally we're very disappointed for Paula, particularly as it means she won't have the opportunity to defend the 5000m title she won in Manchester four years ago.