Jessica Ennis-Hill will be sidelined for up to 15 weeks with the Achilles injury that has
kept her out of the World Championships.
The heptathlete has had the problem all season, although she did compete in the hurdles and long jump at the Anniversary Games last weekend.
Ennis-Hill finishes fourth in 100m hurdles
"Achilles tendons are awkward and there's a period of rest [involved]," said her coach Toni Minichiello.
"If we're lucky then we're looking at a 12 to 15-week recuperation period."
The injury has caused Olympic champion Ennis-Hill to pull out of five events this year and Minichiello says it was not worth the risk for her to compete in Moscow.
"When she didn't respond well after the London Diamond League, the position was that it didn't make sense and you're probably going to cause her more damage and lose the remaining years of her career to struggling with the injury," Minichiello told BBC Radio 5 live.
"As a coach I'm not prepared to take that kind of risk so decisions are made and we pulled her at that stage."
In only her second competitive appearance since winning gold at London 2012, Ennis-Hill finished fourth in the 100m hurdles and eighth out of eight in the long jump at the Anniversary Games.