Britain's former world record holder injured an adductor muscle while warming up at Gateshead on Friday evening - just a week after he made a superb come-back at Crystal Palace following a year out with shoulder trouble.
'It's painful just talking about it,' he said. 'My chances of going to Stuttgart hoping to do any good appear to be very slim. I haven't given up hope yet, but I have to say it looks bleak.'
The disappointment over Backley came on the same day that Roger Black, 400 metres silver medallist at the last world championships in Tokyo in 1991, confirmed that he would definitely not be fit for Stuttgart. Black has finally had to admit defeat by the viral problem that has troubled him all season. It is a big blow for the injury-plagued 27- year-old, who had started the summer feeling rejuvenated after a hip operation.
The London Marathon winner, Eamonn Martin, is also believed to be on the verge of withdrawing from the squad with Achilles problems, while Liz McColgan and Peter Elliott, two more medal hopes, are already ruled out.
Backley's name, ironically, was yesterday included among seven additions to the squad - but medical officials will examine him and other doubtfuls before allowing them to make the trip.
The out-of-sorts steeplechasers Colin Walker and Tom Buckner have been asked to prove their fitness, along with another key 400m man, Mark Richardson, and the javelin girl Shelley Holroyd.
On the brighter side, Preston's John Nuttall (5,000m), Wolverhampton's Andy Tulloch (sprint hurdles) and Brighton's Sonia McGeorge (1500m) were among those celebrating a late call-up as a reward for their impressive victories in Gateshead on Friday.
The Olympic steeplechase finalist Tom Hanlon is also included after his recent upsurge in form. But Steve Cram confirmed yesterday he will make what is likely to be his make-or-break bid to gain the world championship 1500m qualifying standard in Cologne tomorrow, alongside Sale's Kevin McKay, who has still not satisfied selectors of his fitness.
WORLD CHAMPIONSHIPS Additions to Great Britain team: MEN: 5,000m: J Nuttall ; 110m hurdles: A Tulloch; 3,000m steeplechase: T Hanlon; Pole vault: M Edwards; Javelin: S Backley (subject to fitness). WOMEN: 1500m: S McGeorge; Triple jump: R Kirby.Reuse content