A mood of huge optimism has swept over the nation following the stunning victory against Argentina in Sapporo, and Eriksson acknowledges the boost the performance has provided.

"If we play football as we can do, then the players should not fear anyone," he said at his press conference in England's base camp in Awaji Island (click here to view the video).

"But I think at this moment it will be very good to remember what happened after the game against Germany in the qualifiers.

"That was a very good result, but then we played Albania and did our job but did not perform very well and when we played Greece, we did not play very good. We only qualified because of David Beckham's tremendous free-kick in injury-time which earned us the draw we needed.

"We only qualified because of David Beckham's tremendous free-kick in injury-time which earned us the draw we needed.

"I do not want that to happen again - for us not to play well - after achieving an outstanding result."

The message is clear for everyone ahead of the crucial Group F match on Sunday, where a draw would guarantee that England progress to the Second Round.

"If anyone thinks because we have beaten Argentina, one of the best sides in the world, that it will be easy to beat Nigeria, then it will be very stupid and also very dangerous.

"It would be very stupid and very sad to see the team play bad football on Wednesday.

"Nigeria may have no points so far, but they have some very good football players and they can play football. There is no doubt about that."

When pressed, Eriksson is willing to hint at the potential of his side, and the possibilities that the Argentina result has opened up for the rest of the tournament.

"If we can go through, then anything is possible. You never know as all teams normally get more and more tired.

"We could go out or we could be playing in the final on June 30. I always believe and I am very positive, although I don't like to talk about it in public."

However, as ever, any hint of crystal ball-gazing is accompanied by a heavy dose of realism from the England coach.

"I have always said that I would not like to go home after June 12.

"I should hate that, just coming here and playing three games, and I will be relieved if we can get a result on Wednesday."

Stay logged on to TheFA.com for all the latest from the England camp.