If the former Porto boss does leave his post, Ferrnando Hierro and Spanish Under-21 coach Albert Celades will be next in line to step in and take over the role.
"The values of the national team are above everything", he said on Twitter. "We feel obliged to take this decision", Rubiales told a news conference at the team base in Krasnodar.
"He told us five minutes before the press release", Rubiales said. If anybody wants to talk to one of our employees, they have to speak to us, too.
"We have a group of players who have been together for two years to work towards the World Cup and I have been sporting director, so I understand the motivation is huge".
The U21 manager Albert Celades, who is part of the coaching staff with the senior squad in Russian Federation, and director of football Fernando Hierro are two of the possible replacements as head coach heading into the World Cup.
No decision has yet been made over who will take charge, with Spain due to face European champions Portugal in Sochi on Friday.
Asked how he chose to take the high-stakes role with no time to prepare, Hierro, who was already in Russian Federation as Spain's sporting director, responded: 'If I was not convinced of our chances, I would not be here. We are working on it.
"The circumstances are what they are and from now on I accept the responsibility bravely, it can't be any other way". We know we must compete - three games to continue in the World Cup. I have a very clear conscience, and from there we take on the challenge we have in front of us. He is a top coach for me, which made the decision very hard.
"To win is very important, to have the best coach is very important, but above everything is acting in the right way". "It may look like a weakness now, but with time this will make us stronger". The Spanish national team is the team of the Spanish.
"I found out [about the deal with Madrid] five minutes beforehand and asked for nothing to be done, that I was getting a plane and coming here". "It has been a very hard decision, the most hard for me". "I have spoken to them and I can assure you that the players and the the new coaching staff will do everything possible to lead the team as far as possible [in Russia], but it's a complicated situation".
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