Spain defender Dani Carvajal dismissed criticism of Fernando Hierro and insisted the coach was ready to lead the European giants.
Hierro's side were unable to hit top form but still topped Group B at the World Cup in Russia.
The Real Madrid great only took over after the stunning sacking of Julen Lopetegui on the eve of the showpiece tournament, and his team will go into their last-16 clash with Russia Sunday as favourites.
While Bernd Schuster was critical of Hierro, saying the 50-year-old was not a coach, Carvajal defended the Spain boss.
"I think he [Hierro] is more than capable. I disagree with those words from Bernd Schuster," Carvajal told a news conference.
"Those who are watching him are us, and we see him more than capable to manage this national team.
"He is a great coach and we are absolutely behind him."
Spain have landed on what many consider the easier half of the draw in the knockout stage.
While Carvajal acknowledged several favourites – including the likes of Brazil, France and Belgium – were on the opposite side to Spain, the Real Madrid defender said every game would be difficult.
"We must be self critics. We all need to improve, but there are no easy opponents in a World Cup," he said.
"It's true that many favourites are on the other side of the draw, but we've got the other seven from the best 16.
"We must focus on putting a good performance against Russia, on going step by step."