England star Jonny Wilkinson's World Cup campaign could be over before it has even started after his injury jinx struck again to deal the defending champions a potentially shattering blow.

Wilkinson will miss England's opening Pool A clash with the United States in Lens on Saturday due to a twisted ankle suffered in training.

The Newcastle fly-half's latest fitness blow means he is sidelined for the 34th time in 41 Tests since his drop-goal gave England World Cup glory in Sydney four years ago.

Wilkinson's immediate World Cup prospects - and whether or not he will be fit to face pivotal pool stage opponents South Africa at Stade de France on Friday week - now hinge on the outcome of a hospital scan.

England's record points scorer was hurt during a non-contact defence session less than 24 hours after arriving in France.

And while a twisted ankle might not rank on the same scale as two major knee injuries, shoulder surgery, groin trouble, a lacerated kidney and appendicitis - all among Wilkinson's fitness troubles since 2003 - England find themselves playing a depressingly familiar waiting game.

His place in the starting line-up has been taken by Bath's Olly Barkley, with big-money rugby league import Andy Farrell summoned for bench duty.

England will not issue any further medical bulletin until the scan results are known, but number eight Lawrence Dallaglio revealed Wilkinson remained ''very positive''.

Dallaglio said: ''It looked fairly innocuous to me. I think Jonny just went over on his ankle.

''It is disappointing for him because he has worked incredibly hard to get fit.

''He has looked really fit and it is a disappointment for the World Cup he is not starting the competition.

''But I don't think we need to get it too out of perspective. He seemed to get up on his feet pretty quickly, and I think it would be wrong for any of us to speculate too much.

''The priority for England is that Jonny is fit for next week. If his injury rules him out for next week, then it would be a blow, but at this stage we just have to wait and see how he comes out of it.

''I spoke to him at lunch and he is very positive about it.''

Wilkinson's continued misfortune does, however, hand Barkley a golden chance to prove himself as a more-than-capable replacement.

He made his Test debut as a teenager against the USA in San Francisco more than six years ago, but Saturday's encounter at Stade Felix-Bollaert sees him make a World Cup bow.