Manchester United goalkeeping coach Emilio Alvarez has said David De Gea's World Cup blunder against Portugal had no effect on him.
Spain and United keeper De Gea let Cristiano Ronaldo's shot through his hands in the 3-3 draw and has conceded five goals from six shots, but coach Fernando Hierro has confirmed that he will start in the round-of-16 clash with hosts Russia despite some calling for Kepa Arrizabalaga to play.
Alvarez, who oversaw the keeper's breakthrough at Atletico Madrid, told Cadena Ser radio that he was "calm."
"I'm in contact with David, but as coach and friend without interfering in the work of Spain's coaching staff," he said. The mistake against Portugal had no effect on him.
"I've worked with him for many years on a daily basis and we know how capable David is. A goalkeeper has to live with a mistake and to overcome the mistake is nowadays imperative.
"Goalkeeping coaches work on this from a mental standpoint from the age of 11, so that mistake has not affected David in any way. He is calm. He is training well. He is focused. He is very enthusiastic.
"He had prepared very well for the World Cup. He's had his best season since he's been at Manchester United. You can look at the archives and you won't find a mistake made by him like that. But I see him very ready, I see him calm."
Alvarez said De Gea would be upset to be dropped, adding that "nothing surprises me in football" but adding that the United No. 1 has "a capacity to mentally abstract himself from pressure."
Thiago Alcantara, speaking at a Spain news conference, backed De Gea and said his teammates trust in him was "huge."
"Being a goalkeeper is the most unfortunate position because their level of risk is very high," he added. "If you have seen David in recent years, he has proven to be a great keeper. How many times you have you said David saved a game?
World Cup 2018 must-reads
"Do self-criticism, too and value how good he is and how many times he has been the best keeper of the Premier League. To criticise you must be in everything, not only in games but also in training sessions.
"He works like an animal. The trust in David and in the other goalkeepers is huge."
Former Spain goalkeeper Pepe Reina, meanwhile, said criticism of De Gea was "exaggerated" and he expected him to start against Russia.
"David is probably the first that wants to have a great game to be calmer," Reina told Cadena Cope. "He has the confidence and respect of the whole group.
"We haven't been good individually and collectively -- we have to accept it and improve.
"Because of his personality, I don't think De Gea needs help also because he is not experiencing a critical time. I think it's being exaggerated. He has made two mistakes like everyone in this world.
"Changes are not good but I also don't see the reason to make a goalkeeping change at this time. I honestly don't think there will be a goalkeeping change. He is the first one that wants to make amends and help the team. I'm certain that will be the case."