World and European heptathlon champion Jessica Ennis has withdrawn from the Aviva Grand Prix in Birmingham on Saturday.
Ennis has been suffering from inflammation of the left ankle which saw her pull out of two events on the second day of the Aviva Indoor Trials and UK Championships in Sheffield last weekend.
The 25-year-old has undergone treatment for the past few days in an effort to be fit for Birmingham, but progress has been slower than expected.
Ennis said: "With the European Indoor Championships only two-and-a-half weeks away, under the advice of the UKA medical team and in consultation with my coach Toni Minichiello, I have decided that racing this weekend is not going to help the healing process.
"I am working with my team to prepare an intense treatment programme and am putting all of my energy into being in the best shape for the pentathlon on March 4 at the championships in Paris.
"Withdrawing from the Aviva Indoor Grand Prix is not an easy decision and I am really frustrated, but nipping injuries in the bud is really the best thing to do and I really want to be at my best for Paris."
Ennis initially described the injury as an "annoying niggle", but talk of an "intense treatment programme" suggests the problem may be more serious than first thought.
The Sheffield athlete will be a hot favourite to win in Paris and add another gold medal to her increasing collection, but is certain not to take any chances with a world title to defend later this year in Daegu, South Korea.