The air of invincibility surrounding the Spanish national team totally vanished in Brazil this summer when the reigning world and European champions were unceremoniously dumped out of the World Cup group stages.

The 2016 European Championships qualifying process was supposed to give Spain boss Vicente Del Bosque the platform to regroup and return this group of enormously gifted players to the top of international football.

Instead, a shock 2-1 defeat to Slovakia on Thursday night simply highlighted how much work Del Bosque has ahead of him if he is to recapture the dominance Spain enjoyed just a handful of years ago.

So how and why have Spain fallen so far from grace in such a short period of time? La Liga expert Andy West offers his thoughts…

1) IKER CASILLAS

The iconic goalkeeper does little to inspire confidence these days, with his embarrassing error for Slovakia’s first goal on Thursday night a typical example of his current unreliability.

David De Gea is waiting and ready on the sidelines, but Del Bosque is famously loyal to his long-serving players and is keen to avoid further changes in personnel after the summer international retirements of Xabi Alonso, Xavi and David Villa. Casillas might have to make the decision for him.

2) DIEGO COSTA

Del Bosque made a huge effort to convince Costa to switch his allegiance from Brazil and now feels dutybound to persist with him. But Costa, who relishes the open spaces of counter-attacking, simply does not suit the team’s style of play.

For Del Bosque to genuinely change La Roja’s whole approach simply to suit one man would be a major decision, but unless that happens it’s tough to see how Costa can transfer his club form into the international arena.

3) CENTRAL DEFENCE

Sergio Ramos and Gerard Pique were the established starting pair for a long time before Pique’s loss of form made his place far from guaranteed.

Another significant issue is the fact that Pique is an outspoken supporter of Catalan independence, making many fans – and perhaps even team-mates – suspicious of his commitment to the Spain team.

But options are minimal, with Raul Albiol rarely looking good enough and Marc Bartra hardly ever starting for Barcelona.

4) LEADERSHIP

For all the wonderful talents within their ranks, Spain’s historic three-time championship-winning team was largely built around just one man: Xavi.

Now the pass master is gone, there is nobody to give an aura of being in charge and in control.

Koke (above) should be the inheritor of Xavi’s role in the centre of midfield, but he is still finding his feet at international level and does not appear ready to take the responsibility of energising the team when they are struggling.

5) OVER-CONFIDENCE

After equalising inside the last 10 minutes, most teams would have settled for a 1-1 draw from a tough away game in front of a partisan crowd against a dangerous and in-form Slovakian outfit.

But Spain believe they can win every match and were so hell-bent on finding the winner, they left themselves exposed to Slovakia’s decisive counter-attacking winner.

A more measured and balanced approach, especially while the new-look team finds its identity, would be sensible.