Spain coach Vicente del Bosque admitted on Friday that he is still to decide how to configure his team for Saturday's quarter-final against France.
"They will be very difficult opponents," said Del Bosque. "There are still doubts about the starting line-up, but that's a healthy thing.
"It's not just today (Friday). I've always had 23 players at my disposal. All of them are great players and important players for their clubs, and I could use all of them. That's why I have doubts. It would be bad to be sure of everything."
Del Bosque's chief selection dilemma is thought to concern the team's attack, with Fernando Torres hoping to hold onto his role at the tip of Spain's formation despite competition from Barcelona midfielder Cesc Fabregas.
Spanish headcoach Vicente Del Bosque gestures during a training session at the Donbass Arena stadium in Donetsk on June 22, 2012 on the eve of their quarter-final match against France during the Euro 2012 football championships. AFP PHOTO / PIERRE-PHILIPPE MARCOU