Jess Ennis-Hill has been forced to pull out of the World Championships in Moscow because of an Achilles injury.
The Olympic gold medalist at the London games last year has struggled with the injury all season and only made her return to action earlier this month at a low-key event in Loughborough.
The 27-year-old struggled through two events at the Anniversary Games at the Olympic Stadium last weekend, finishing last in the long jump and 4th in the hurdles, which prompted her to admit she was "disappointed" with her performance.
UK Athletics chief Neil Black had tipped Ennis-Hill to take up her place in the World Championships following her appearance in Stratford, however now she has conceded defeat in her race to be fit in time to compete.
"To say I am gutted is an understatement," she said.
"No athlete likes to miss the opportunity to compete at a major championships - they don't come round that often."
"Up until now we have been focusing on managing the pain so I can train and get myself in shape to win in Moscow," she said. "The time has now come to stop chasing fitness and look to cure the problem."
The Sheffield-native had previously admitted she would only take part if she felt 100% fit.
Coach Toni Minichiello added: "We have not seen enough improvement that would have made completing the two day, seven events of the heptathlon possible.
"There are nine global medals up for grabs over the next three years not including Moscow. So a long term view has been taken."
Had Ennis-Hill been able to compete in Moscow she would have been hopeful of taking gold after main rival Tatyana Chernova was also forced to pull out with a knee ligament injury.
As it stands Katarina Johnson-Thompson will fly the flag for Britain in the Heptathlon at the World Championships in Moscow, which gets underway on August 10.