The 33-year-old plays down suggestions that there is a great weight of expectation on the shoulders of the national side following their success in recent yearsIker Casillas thinks that Spain "have earned the right to fail", dismissing the pressure of trying to win back-to-back World Cups.
The Real Madrid goalkeeper was part of the trophy-winning side in South Africa four years ago, as well as the team who triumphed at the European Championships in 2008 and 2012.
Casillas will also likely be Vicente del Bosque's No.1 in Brazil as La Roja seek to continue their recent dominance in international football.
However, the 33-year-old knows that Spain - in a group that includes Australia, Chile and Netherlands - are just one of a number of teams with a realistic chance of winning the tournament.
"We have a difficult group. In addition, our first two matches are against [Netherlands and Chile] who, in theory, we will be vying for qualification with," Casillas told reporters.
"I think we need to go to Brazil without any pressure. In these last six years we haven't done good things, we have done sensational things. We have earned the right to fail.
"We are going with the idea of competing and defending our title but we know that there are 31 other teams who want to do the same and it won't be easy."
Casillas believes that the Dutch could be a threat in the latter stages, stating that Spain's tough opener against Louis van Gaal's men will stand them in good stead.
"From what I hear from people, I think the Spanish fans are delighted with the last six years they have seen. The majority thought they would never see anything like it," he added.
"We start against Holland, who should be the other big favourites along with us. However, I think that having to start strong gives us motivation. It means that the team must be in the right mindset from the first day."