Del Bosque's team became the first side in the history of the European Championship to secure back-to-back titles following a 4-0 thrashing of Italy in the final in Kiev.

However, del Bosque, who also led Spain to glory at the 2010 World Cup, said he was not always sure that the team could win the title in Poland and Ukraine and gave the example of the semi-final contest against Portugal, which was settled by a penalty shoot-out.

"Of course I had doubts," Del Bosque told Kicker. "It is the small details that decide things.

"Bruno Alves' penalty hit the cross bar, and (Cesc) Fabregas' penalty came in off the post. So we were lucky. But I never had any major doubts about my team's quality."

Prior to the tournament, it was feared that the tense relationship between Real Madrid and Barcelona players would have an impact on the atmosphere in Spain's dressing room, but del Bosque insisted that was not the case.

"This team has shown that they enjoy going further, and above all, that they are not satisfied," he said. "The behaviour of these players, especially amongst themselves, was exceptionally good.

"We were together for 40 days and there were no incidents. Everyone, including the substitutes, was moving in the same direction."

With the end of the careers of Xavi, Andres Iniesta and Iker Casillas getting closer, there are fears about Spain's ability to maintain the same level of form in the future.

But del Bosque said he had complete faith in the players that are breaking from the clubs' youth ranks.

"Those players are irreplaceable," the 61-year-old said. "Without them, there would be no treble. But I am sure that there are players who can take their places due to our excellent youth work.

"You can see the wealth of talent in the Olympics team. And in the current first team, players like Cesc Fabregas and Santi Cazorla need to wait to take up a bigger role."