Madrid: Spain's goalkeeper and captain Iker Casillas admits that the defending European and world champions could be their own worst enemies as they seek more glory at Euro 2012.
"The sporting side of things is not a problem, because this team is good enough to beat anyone," Casillas said at a press conference in the Austrian town of Schruns, where members of Spain's preliminary squad have been training this week.
"The mental aspect could be an issue, because we could be our own worst enemies - it all depends on the level of desire and the effort we put in to try and win the competition.
"It will be difficult to retain the European Championship title. Other teams know how we play, they study us more.
"Every game against us will be the biggest game for our opponents and they will be more motivated than usual," Casillas added as Spain prepare to take on Italy, Croatia and the Republic of Ireland in Group C.
Spain coach Vicente Del Bosque will name his final 23-man squad on Sunday, once the Copa del Rey final between Barcelona and Athletic Bilbao is out of the way.
With so many key players involved in the final match of the domestic season, Del Bosque will be the last of the 16 coaches preparing for Euro 2012 to have his whole squad at his disposal.
However, Casillas says that must not be used as an excuse in the event of failure.
"It is true that this training camp is a little different to what we are used to but that does not mean it is worse for any reason," Spain's most-capped player added.
"It is not really a big deal because those of us in the squad have known each other well for a long time."