IKER CASILLAS has become accustomed to existing within the centre of firestorms.

The role of scapegoat is something he has stoically learned to accept.

Throughout his trials and tribulations of late, though, he has always found a loyal friend in his national coach, Vicente del Bosque. That relationship, as the alarming collapse of Spain's once-impregnable empire continues at pace, is about to be tested to the full.

Casillas was the face of La Roja's rise to become, arguably, the best team the world has ever witnessed. As Spain's golden era becomes ever more a thing of the past, however, the lynch mob smells blood. At the end of a week in which a forensically-dissected television interview put him back under the spotlight at club level with Real Madrid, fresh failings on the field have dragged Casillas perilously close to being permanently replaced as his country's first-choice goalkeeper after a record-breaking 158 appearances.

Xavi Hernandez, Xabi Alonso and David Villa wisely called it quits in the wake of a shameful first-round exit at last summer's World Cup.

Casillas, who branded his calamitous display in a 5-1 loss to the Netherlands as "the worst performance of my career", might well have been advised to do the same. But he was hurt by events in Brazil. He wants to make amends.

After appearing to recover from a spell at Real Madrid earlier this term in which he was being jeered by a section of his own supporters, the roof caved in against Slovakia in Zilina on Thursday night. After just 12 minutes, the 33-year-old lost track of a 30-yard shot from Juraj Kucka that swerved in transit and allowed it to go straight through his left glove and into the net.

Spain went on to lose 2-1. Casillas was not entirely to blame for the defeat, their fourth in six games and their first in a qualifying fixture for eight years. Spain enjoyed most of the possession and had 20 shots to Slovakia's five, but they did lack freshness, bite and invention.

For all that, questions about Del Bosque's future do not top the agenda. It is Casillas copping most of the flak with the Spanish sports newspapers. Marca branded his early error "a fiasco" with Sport making great mention of just what a mess he had made of it all within an evening of "ridicule".

"Normally the focus of a game is on the goalkeeper," said Del Bosque. "In Iker's case there's no solution. There's too much focus on him. I don't think he's 'lost his angel': he made a great stop after 15 minutes. He's a great player, and one that all Spaniards should be proud of."

A poll on Marca's website had 83 per cent of almost 16,000 respondents insisting the time has come for David de Gea to be handed the starting jersey.

Chances are De Gea will step between the sticks for tomorrow's Group C match in Luxembourg. It is an easy game in which to give him an outing. Del Bosque has a major decision to make, though, before next month's visit of Belarus.

"I didn't see the goal well from the bench, but I think the ball made a strange movement and deceived Iker," said Del Bosque after the dust had settled in Zilina. "Casillas had saved a good chance from Slovakia in the previous move. This is football. We cannot fault players."

The truth, however, is that Casillas seems forever damaged by events at his club over the past couple of years. His spats with Jose Mourinho, which saw him replaced by Diego Lopez, still haunt him. An interview staged earlier this week with Canal Plus in Spain is only likely to inflame those some the Real Madrid support.

Casillas, whose partner Sara Carbonero is a television sports presenter, was blamed during Mourinho's bitter and divisive final season in charge as 'a mole'.

"Some people used Sara as an excuse to launch attacks on me," he said. "They started saying I was leaking information to my partner, so that she would spread it. The public are free to do what they want, but it [the booing] also hurts."

He also revealed that he was left to feel "isolated" by the Real Madrid president, Florentino Perez, after breaking his hand in January 2013 when Mourinho brought in Lopez from Sevilla. He claims he wants to end his career in the Bernabeu, but his long-term replacement is already there in Keylor Navas, signed from Levante in a €10m six-year deal.

The Spanish newspapers are already carrying analysis from Navas' native Costa Rica, stating that he is biding his time and playing contentedly in the Copa del Rey because he expects Casillas to leave at the end of this season.

In the meantime, Iker continues to look toward France 2016. "I'm dreaming about it because I didn't play well in the World Cup," he said. "I did not like how I played in Brazil."

Few did. At this moment, it is hard to see him having his wish.