Heptathlete Kelly Sotherton has pulled out of next month's World Championships in Berlin because of a heel injury.
The 32-year-old has struggled with her fitness all year but was optimistic of recovering after coming through last week's trials in Birmingham.
"It's disappointing as this will be the first summer championship I have missed in my career," said Sotherton.
"I could probably go to Berlin and get in the top eight, but I only want to go if I can really contend for a medal."
It has been a frustrating 12 months for the 2004 Olympic bronze medallist, who has been forced out of a number of events because of injury since finishing fourth at the 2008 Beijing Games.
The Isle of Wight-born athlete - based in Birmingham - has been hampered with back and foot problems and although she came through the long jump and shot putt in the trials, her heel was still causing pain during a running session last Friday.
606: DEBATE" Why are so many of GB's athletes out of Berlin? "
Despite not having the chance to improving on the bronze she won at the Worlds in Osaka two years ago, Sotherton revealed she is focusing on bigger goals.
"I have got to think about my long term health and in particular everything being okay for London in three years. I want to give myself every chance of competing at the 2012 Games," stated the Commonwealth Games champion.
"I am going to speak to specialists to look at possible surgery. It is an injury that can be patched up, but it's more important to find a long term solution, get myself fighting fit again and look to return to full training in the winter."
UK Athletics head coach Charles van Commenee faces an anxious fortnight before flying to Germany with a number of other high profile athletes facing a fitness battle for the Worlds.
Olympic 400m champion Christine Ohuruogu pulled out of this weekend's London Grand Prix with a hamstring injury, while 400m runners Martyn Rooney, sixth in Beijing, and Tim Benjamin are also struggling with hamstring problems.
With Mara Yamauchi (foot) already missing in the marathon line-up, Dutchman Van Commenee may be reliant on the likes of triple jumper Phillips Idowu and heptathlete Jess Ennis grabbing gold.
The World Championships start on 15 August and 23-year-old Ennis has an excellent chance of becoming World heptathlon champion, having impressed in all competitions since recovering from a fractured foot.
Sotherton, who has previously hinted that she could give up heptathlon for the long jump or 400m relay for London 2012, added: "I wish the whole team well for Berlin.
"I wish Jess Ennis all the very best too. I know she can win gold for the team.
"This weekend has also seen lots of medals being won by British athletes at the European under-23 championships, there are lots of emerging names and I hope they can do well in Berlin."
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