Jonny Wilkinson has warned England they must shake off the loss of Andy Farrell and get on with the job of defeating Australia.

The fly half, whose drop goal won the World Cup in Sydney four years ago, urged his teammates to be ruthless after Farrell withdrew from tomorrow's quarter-final with a calf injury.

Wilkinson said: ''It's not an ideal scenario and it's tough for Andy. It's hugely disappointing for him and for us.

''But we've got to be ruthlessly vigilant for this game and we've not got time for those feelings right now. It is a disruption but we can get over it.''

England head coach Brian Ashton will decide this lunchtime who takes Farrell's place at inside centre.

Wilkinson, however, insists any change will be seamless.

He said: ''Whoever comes in it will be different but there is a system in place. There's a cohesive feeling about the group. It will be important to get on the wavelength of the person who comes into that slot.

''I'd expect to be given a heads-up on it but there is no real preference. I have experience of playing alongside Olly Barkley and appreciated his input in a period where I have been finding my feet.

''I have experience with Mike Catt over the years. He's someone I've respected massively. I've always enjoyed his unselfish approach. I'm excited about whatever happens.''

Whoever slots in beside him, in what has been a problem position for England, Wilkinson will face a 21-year-old opposite him in Berrick Barnes, for whom he has the ultimate respect.

Barnes, who admits to having learned from Wilkinson's coaching manuals, has filled in for the injured Stephen Larkham at this World Cup and reminds many of Wilkinson seven years ago.

Wilkinson, just five behind Gavin Hastings' World Cup points scoring record of 227, said: ''Barnes has taken a huge role with a team which carries huge expectation and filled some big boots in Stephen Larkham.

''To come in and lead the team at that age is incredible. I always had trouble with stamping my authority. He looks like he completely understands the game. He has that youth and freshness but seems to have a great deal of experience too. I don't know where it has come from.''

On the fact that Barnes has read his books he added: ''I wouldn't have known how to tell someone to come in and do what he's done. It's humbling for someone to say that. I grew up watching people and thinking how good they were but always wanting to be myself. The only difference I see between us is that I'm a bit older.''

There is another crucial difference. England's points-scoring machine already has one World Cup medal in the cabinet, and despite almost three years out of the game with injuries still bears the expectation of a nation.

Wilkinson said: ''I would have hoped to have played more. I've done most of my learning off the field. It's given me a greater awareness of what these occasions mean and I have a deeper understanding and respect for what it takes to be here.''

It was typically introspective Wilkinson, a man who analyses obsessively, although these days there are the occasional light moments such as when he was told about Aussie Stephen Hoiles's answer to the question: How do you stop Wilkinson?

Apparently Hoiles said ''Poison,'' on hearing which Wilkinson picked up his bottle of water, shook it and studied it.

Mainly, however, Wilkinson was attending to his goal-kicking practice, talking about ''crunch time'' and revealing the secret of success was to ''work like hell."