World Cup-winner and Eurosport expert Neil Back believes that England will win their semi-final against France - and may even become the first nation to retain their trophy.

I said last week that England had to find a performance better than any they have played since the last World Cup in 2003 - and they did it. That performance was always available to England. They were able to up their level when it mattered.

It is the first time that England have put together three wins back to back since the last World Cup. You could see the smiles on the faces of the England players and coaches after the pool games against Samoa and Tonga - it was a weight off their shoulders.

Winning is a habit and there is an extra spring in their step now. You could see that confidence against Australia. They knew that to lose any of those games would mean that England were no longer champions of the world.

It was an unbelievable weekend, with the underdogs - England were underdogs, as were France, Fiji and Scotland - showing what they could do, and amazingly two of them went through.

It was a good win against top-quality opposition in Australia. The injury to their fly-half Stephen Larkham cost them. The young lad [Berrick Barnes] was pressured by England and lost his way a bit. This showed when with about an hour gone he tried a drop goal from 50 yards. Australia were chasing the game and it began to show.

My perception of [coach] Brian Ashton after the weekend has not massively changed to be honest. If England now beat France then my view of him will change.

Now they need to back up the weekend's result, which will be a big test. They targeted Australia in the scrum and punished them physically - they must look for the weakness in France, which is certainly not in the set piece.

I truly believe that England will win the semi-final. All their players are fit but they need to raise the bar again. They need to concentrate on more than winning the scrum - they need to provide the platform to win and lose the ball, but also now need to execute when they have it. If they kick poorly against France, as they did at times in the pool stage, they will be punished. But they are sitting very comfortably now.

[France coach] Bernard Laporte is famous for his selections. I wish I knew how his mind worked. It seemed against the All Blacks he threw all his backs in the air and they played how they landed.

The French are always either up or down - on their day they can beat anyone in the world. They proved that in 1999 [when they came back to beat the All Blacks]. It was not a massive shock that they beat NZ on Saturday: if anyone was going to do it, it was going to be France.

Laporte does know how to beat England. France turned up in the Six Nations expecting to win easily and England turned them over. He will not underestimate England this time - it will be a titanic clash and I expect a great match.

Mentally the All Blacks lapsed - they had a bad day and made mistakes. They came into the World Cup ranked number one and every team rested players against them [including Scotland] - as such they weren't really tested until the quarter-finals.

However losing both number 10s was a huge factor - I believe that had Dan Carter, an exceptional player, remained on the field, they would have won the match. Without question that impacted upon their performance.

Before the tournament [recently sacked] Graham Henry prepared the team well both mentally and physically and was praised for the strength in depth of his squad. However now he is being criticised for the very same things that he was praised for last week. Such is the tradition associated with New Zealand, his job was always on the line.

South Africa against Argentina [in the other last-four tie] will be an intriguing game. I hope that the Springboks play with fluidity and don't take Argentina on physically because they are better than that.

Argentina will put them under pressure. The wind has not been knocked out of their sails by the close call against Scotland in the quarter-finals. Marcelo Loffreda is a cunning, experienced coach. Things are always going to get tougher later in a tournament and now it is about them keeping calm under pressure and minimising their mistakes.

The World Cup is wide open. A week ago, if you'd asked me if England could win it, there would have been a massive pause. Now that pause is much shorter.

Eurosport