By Rob Hodgetts

Johnson's reign as World Cup-winning captain ends on 20 October

Martin Johnson says England must forget all about defending the World Cup and concentrate on stringing some good performances together.

England have been in disarray since winning the trophy in 2003 and are still experimenting with their best XV.

And Johnson insists the warm-up games are "vital" to building some form.

"England can't worry about retaining the trophy. That was four years ago. They need to concentrate on now," the former skipper told BBC Sport.

England entertain Wales on Saturday before facing France at Twickenham on 11 August and in Marseille the following weekend.

"I was in France recently and people said they didn't know what to expect from England," said Johnson, who captained England to glory in 2003.

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"You can't underestimate or overestimate them because we don't know the team or how they'll play.

"They don't have to win all three warm-up games. They could play very well and still lose in France but performing well is key."

England are in Pool A alongside South Africa, Samoa, Tonga and USA.

"If they can perform somewhere near their potential, they can beat the likes of Samoa and South Africa to get into the knockout stages," he said.

"Good performances will win the games that will get you to the final. Then you can worry about how to win it."

England are still rebuilding following a host of retirements and long-term injuries since beating Australia in the 2003 final.

We know England can play better Martin Johnson World Cup-winning England captain

Victorious coach Sir Clive Woodward quit his post in September 2004, and his successor Andy Robinson oversaw a disastrous 25-month spell in which England lost 13 of his 22 games in charge.

Brian Ashton replaced Robinson in December and England showed glimpses of a recovery but losses to Ireland and Wales left them third in this year's Six Nations.

Ashton then took a vastly understrength party to South Africa in May where England, depleted by injury, illness and club commitments, lost heavily in both Tests.

Johnson, speaking at official sponsor Orange's Rugby World Cup preview event, said England need to build consistency and concentrate on accuracy, reducing the number of mistakes and keeping pressure on the opposition.

And he stressed that the leaders in the team needed to take control on the pitch and be able to switch game plans accordingly.

"When you look at the likes of Phil Vickery, Martin Corry, Lawrence Dallaglio, Jonny Wilkinson, Mike Tindall and Jason Robinson, you start getting a core of leaders and you think, 'We've got something here'," he said.

"A lot of these guys are still playing good rugby and they've got four years' more experience.

"But the other guys also have to play; guys like Joe Worsley and Lewis Moody. They're not young any more, they've got to stand up.

"We know England can play better. It's not the way they're playing; they're trying to do the right things.

"They've got a very strong squad of players but they need to go out and start playing at that level that enables them to win games."