Spain boss Vicente del Bosque is set to wield the axe ahead of the do-or-die clash against Chile on Wednesday.
Barcelona duo Gerard Pique and Xavi may lose their places in the starting line-up but Del Bosque is expected to keep faith with goalkeeper Iker Casillas despite his horror show in the 5-1 defeat by the Netherlands.
Spain know only a victory against their Group B opponents at the Maracana in Rio de Janeiro will suffice and Del Bosque said the team "are really hurting".
He said: "We still have a chance to progress in the World Cup but this situation has made a response from the players necessary if we want to advance."
Barcelona midfielder Andres Iniesta said the days since the Netherlands defeat had been agony, and pointed out that Spain had lost their opening match of the last World Cup - 1-0 to Switzerland - but still went on to win the tournament.
He said: "I wished we had played one or two days later because the waiting has been really hard.
"We must forget what has happened and put it behind us. We have two matches that are now like finals. We had a similar situation at the last World Cup and will give it our very best to win and get to second phase.
"Chile are a difficult team. We have to defend, fight one versus one and hope our creative players can make the difference."
Spain began their triumphant 2010 World Cup campaign with an ignominious 1-0 defeat at the hands of Switzerland
Meanwhile, Spain's third-choice keeper David de Gea, the Manchester United player, is still injured, according to Spanish team officials.
Chile coach Jorge Sampaoli said he would make a decision close to kick-off on Juventus midfielder Arturo Vidal, who only played for the first half of the 3-1 win over Australia.
Vidal had knee surgery a month ago and is still getting back to full fitness.
Sampaoli told a news conference: "We analyse his situation every single day. We know he's recovering now, he feels much better and he's here because he's really dedicated and willing to play."
Sampaoli said Spain will be fighting for their lives.
He added: "I think they will be difficult to beat. Don't forget they're one of the best teams in the world.
"I'm sure the game will be quite different because Spain are really strong and I'm pretty sure the Spain coach will have some sort of strategy."