Jonny Wilkinson faces an intense fitness battle to make England's crunch World Cup clash against South Africa at the Stade de France.

While the Webb Ellis Trophy holders should launch their campaign with a routine Pool A victory over the USA in Lens on Saturday, Wilkinson will once again be battling his injury demons.

The latest setback of an injury-littered career since his drop-goal saw England crowned world champions almost four years ago has been revealed as ''a lateral ankle ligament sprain''.

The Springboks showdown is just eight days away and Wilkinson appears to be struggling.

''Following an X-ray and a scan yesterday afternoon and a clinical review this morning by the England medical team, it has been confirmed Jonny has suffered a right lateral ankle ligament sprain,'' said an England spokesman yesterday.

''He will receive intensive treatment over the next few days, and a further update will be issued next Tuesday.''

News of Newcastle Falcons fly-half Wilkinson's demise rapidly reached the Springboks, who are settling into their Paris base ahead of Sunday's game against Samoa at Parc des Princes.

South Africa coach Jake White said: ''They are obviously not prepared to risk him against the USA.

''He is one of the best fly-halves in the world, and that can be proven by him not playing rugby for so long and then in his first Test match back (last season) he is man of the match against Scotland.''

USA coach Peter Thorburn said: ''We haven't seen the best of Wilkinson for two or three years. He has just been dogged by injury, so he has never been at full flight.''

While Wilkinson finds himself in the treatment room rather than on World Cup duty this weekend, England - and his replacement Olly Barkley - are thirsting for action.

Shaun Perry, Wilkinson's half-back partner against America until the Newcastle star was hurt during training, said: ''It doesn't really change anything in terms of the game plan.

''Jonny is a legend and you cannot take that away from him. He has that presence about him when he is playing.

''But I played alongside Olly against the French at Twickenham last month and we are looking forward to going out there and taking that partnership a bit further.

''We have been together for ten weeks, so it is not hard to build a relationship in training.

''Olly is a great player. He bosses the forwards well and he bosses the backs well, which is what you need.

''As far as I am concerned, nothing changes. We've got our defensive system in place and no matter who comes in or goes out, that system is there for a reason and that is what we all stick to.

''We know it is going to be a physical game on Saturday and we will need to stick to our game plan, execute it well and the results will come.

''The World Cup starts for us this Saturday and we've got to get a win under our belts, get confidence and move on to next week."