The most striking aspect of the opening week of this World Cup has surely been the difficulty many of the tournament favourites have had to win their games. Something has changed. And the key words here are “intensity” and “belief”.

Smaller nations now believe in their capacity to cause problems and to challenge the traditional powers of world football. I was struck, for example, by the terrible disappointment of the Tunisians after losing to England. These so-called smaller nations really have the belief they can do something against the big boys.

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We saw the changing face of football with the performances of Iceland at the last Euros and here in Russia we saw them holding Argentina to a draw. We saw the victory of Mexico over Germany, a triumph for them tactically and built on belief, too – the idea that there was no reason why they should not pull off an upset, even if it was the world champions they were up against.

I remember we had a terrible start to the 2002 World Cup, losing to Senegal when we were the reigning world and European champions. In modern football all the teams are capable of getting organised and causing problems. The underdogs are not scared any more. Physically they are ready to compete with the bigger nations and now we will see if their energy levels will last and if they can repeat these performances.

Of all the favourites I think I was most impressed by Spain, even though they failed to hang on for the win over Portugal. The Spanish showed that physically and tactically they are ready for this World Cup. They made a couple of defensive errors that cost them dearly but they played with great intensity and this was the highest level of football I have seen so far at the tournament, even if they struggled to beat Iran. And Spain know they will not come up against Cristiano Ronaldo every game!

We saw Brazil were in difficulty in their draw against Switzerland. They have this great capacity for dribbling, of course. It is in their blood but there was too much individual play and not enough for the team. They do not play collectively. They are not yet a team and I was expecting more from them. While Philippe Coutinho tended to use the ball intelligently, Willian was completely transparent.

Facebook Twitter Pinterest Iceland showed against Argentina that the smaller nations now have no fear against the superpowers of world football. Photograph: Christian Hartmann/Reuters

Neymar gave off the impression he was playing by himself. Whenever the ball came to him he slowed the game down, irrespective of whether it was the right thing to do or not. Because he knows he has the talent to change games, he gives the impression that he wants to be the one to do that something special. But he has to understand it is not like that at international level. He might be the greatest player but he has to think of the collective.

He has to think of his teammates and play with them, using one-twos and triangles to move forward and make those differences. The one time he did that, down the left with Marcelo and Coutinho, brought about Brazil’s goal. But that was not enough.

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France, meanwhile, played a 4-3-3 to use the skills and pace of Kylian Mbappé and Ousmane Dembélé against Australia but once again we saw that, when Olivier Giroud is not there, we miss him. When he came on we switched to 4-4-2 and looked better balanced, so now my friend Didier Deschamps has a tricky situation to resolve and he has opted to let Antoine Griezmann play off Giroud. One thing is for sure, France did not make good use of the ball and will have to do better than against Australia if we are to go far. For now, we know a win over Peru should see us through to the next round.

Harry Kane saved England and I saw some good things in their performance. But one could tell there was a lack of experience and perhaps the lack of a leader on the technical side – I expected more from Dele Alli, for example. Let us just say that I did not see anything to make me think England can become world champions.

The Belgians, on the other hand, were convincing against Panama. Where they were a bit disappointing at Euro 2016, one can see now they have gained in maturity. They got over a sluggish start to show a lot of quality in their opening game.

Here is a group of players who know it is now or never for their generation and I sensed there were several players ready to take responsibility. There is so much talent in the Belgian team, and a real presence in the penalty area. I know it was only Panama but I was impressed by the Belgians and you sense they are capable of going a long way if they stick together.