La Roja's No.1 believes the current group Vicente del Bosque has at his disposal is very special but they were fortunate to beat Italy in the Confederations Cup semi-final
The 32-year-old goalkeeper made some fine saves to help his team take the Azzurri all the way to penalties and secure a spot in the final against Brazil.
Following Leonardo Bonucci's miss for Italy in spotkicks, Jesus Navas scored to secure a 7-6 win for Spain and the Real Madrid man admits they rode their luck at times but the fans were witnessing a very special era in Spanish football.
"This generation is unforgettable. Lucky for the Spanish to have seen another win and we're in the final," Casillas said to Tele-5.
"The truth is it was very difficult to win. Italy had made an excellent approach. We tested Buffon as well but they placed us in trouble.
"The thing about the shoot-out is it is a lottery and we have been lucky enough to win. My team-mates have had full success on the penalties and they [Italy] missed one."
Casillas told reporters after the game that it could have easily been Cesare Prandelli's men who were to take on the Selecao.
"Again, we have to admit Italy played a great game. They could be up here talking about an Italy-Brazil in the final if not for a few bounces of the ball," he said.
"We have to recover, physically speaking. We're used to playing games on Wednesday and then on Sunday so we have no excuses not to be match fit.
"Italy had a very good style of play that we didn't expect, defensively they left a few gaps and we had chances to score. Navas was close in the second half of extra time. I'm sure that Brazil, however, will not have that particular style of play against us."
Having been pushed all the way through extra time Casillas admitted his side are fatigued and will need time to recover for Sunday's final in Rio de Janeiro against the hosts.
"We are very tired. We need to rest. We will have to face Brazil in the Maracana. We will try to play a good game."