Vicente Del Bosque tries to keep Spain's doubters at bay at Euro 2012

Vicente del Bosque in pensive mode at yesterday’s press conference (AP)

All around Spain's training base there are banners reminding Vicente del Bosque's team that history does not win tournaments. Instead, the slogans state that "concentration", "talent" and even "humility" will be the key ingredients if Spain are to win a third major championship in a row.

Doubt does not win much and, for the first time, doubt has started to seep into the Spanish camp. For the 53 minutes between Antonio Cassano putting Italy ahead against Ireland on Monday night and Jesus Navas thumping home the winner from a yard out, the world and European champions were a goal away from elimination – and Croatia had more than one chance to score it.

Polls conducted as the Spanish fans streamed down the steps of the PGE Arena in Gdansk for the last time, bound for the less-familiar streets of Donetsk, were clear. They wanted Del Bosque to stop the experiment of playing without a recognised striker, which he had employed for most of the opening fixture against Italy and for the final half-hour against Croatia.

"Everybody feels they can be a coach but I would ask them to relax," said Andres Iniesta, whose role in breaking the deadlock in Gdansk was pivotal. "All teams have difficult moments and Spain is no exception.

"We were more tired than in previous matches. There were moments of quality in our game but there were also moments of doubt because we knew that one goal from Croatia could eliminate us."

Like Iniesta's club, Barcelona, Spain suffer from the perception that every game has to feature goals created by a series of dazzling passes, finished off with geometric precision. Sometimes, you yearn for them to lump it up to Fernando Llorente, Athletic Bilbao's big No 9, and see if he is as effective as he was against Manchester United.

Like Arsène Wenger, who was watching from the stands in Gdansk, Del Bosque is determined to defend the purity of his football. "We should have faith in the style of play that has taken us this far," said the Spain manager yesterday. "We have plenty of resources to deal with teams who concentrate only on defending. If we had a bad match, Croatia had a worse one.

"People expect too much. A few years ago Spain were not well rated but now everyone expects everything. David Silva and Iniesta need to move into spaces and against Croatia the spaces were very small and, although some of the passes went astray, they did so by millimetres. People may lose faith in us but the most important thing is that we have faith in ourselves."

Nevertheless, as he walked through the corridors of the PGE Arena and into club management, Slaven Bilic believed he should have been preparing for a quarter-final in Donetsk.

"People are going crazy about Spain but the world moves so fast that we forget about the detail," said the now former manager of Croatia. "It is going to be very hard for them to win this tournament. Italy have shown that and so have we.

"When they don't play with a striker, they keep the ball more and they come at you from the flanks – and then your defenders just have to cover their own zone. When they play a striker, you have to defend your box and the wings. Against us, it was mainly [their goalkeeper] Iker Casillas who saved them. They looked vulnerable."

Certainly, Spain seem vulnerable to strangulation. Italy and Croatia both flooded their midfield and there was a photo doing the rounds of the Spanish camp that showed Iniesta, alone, surrounded by five members of the Italian team. Iniesta was likened to the Japanese cartoon footballer, Oliver Atom. "Perhaps not Oliver Atom," Iniesta smiled softly. "This will be hard and if, God willing, we get to the 2014 World Cup, it will be even harder.

"This team has a perception that it has to win every game 3-0. I'd actually prefer to be in this situation than in previous tournaments when we were packing our bags after one bad game. But the fact is that, when you are champions, it is very difficult to raise your game to another level."