Spain coach Vicente del Bosque admitted on Friday that he is still to decide how to configure his team for Saturday's Euro 2012 quarter-final against France.
The reigning world and European champions, Spain will start as favourites at Donbass Arena in Donetsk, where both teams will be competing for the right to tackle Portugal in the semi-finals.
France coach Laurent Blanc has vowed to change his line-up in order to counteract Spain's likely dominance of possession, but his opposite number said he was in two minds over his own team selection.
"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.
Asked to comment on the likelihood of France adopting a defensive approach, Del Bosque said he did not think Blanc's side would be prepared to abandon their attacking instincts.
"I have a hard time believing that they are just going to close up their defence," he said.
"They have players who like to play and take the initiative. They will want to beat us. I just hope the match will turn out well.
"France's coach is a good coach. He has great players at his disposal. The match they lost against Sweden doesn't count for anything. They're a good team and they hadn't lost for a long time before that match."
France saw a 23-match unbeaten run come to an end with a 2-0 loss to Sweden on Tuesday, which reportedly sparked a shouting match in the French changing room after the game.
It prompted fears that the team could be succumbing to the same internal conflicts that fatally undermined their 2010 World Cup campaign, but Del Bosque said he did not expect it to have a bearing on Saturday's game.
"Relationships in teams are never idyllic," he said.
"You have to work hard to have good relationships within the team. Some players can be more difficult to cope with but as long as they play well on the pitch, that's the important thing.
"I don't know France's players but I don't think it will influence tomorrow's match in any way."
His remarks were echoed by centre-back Sergio Ramos, who is in line to win his 90th cap on Saturday.
"I think that at a tournament like this, the objectives are greater than anything that can happen in the changing room," said the Real Madrid defender.
"We are professionals and we have to keep our cool. We're not here to fight but fights happen in every family and every home, and we're no different."
France prevailed 3-1 when the sides last met in a major tournament, in the last 16 of the 2006 World Cup, and they have never been beaten by Spain in a competitive fixture.
Despite Spain having swept all before them over the last four years, Del Bosque says their poor record against their neighbours in international competitions cannot be ignored.
"Everyone thinks we're the favourites because we won the European Championship and the World Cup," he said.
"But France have always been better in competitive matches, so we will just have to see tomorrow if we are able to change history."