The Iranians arrived in Kazan on Monday.
That was soon ruled out and it was suggested he could return for Spain's final Group B match against Morocco, but Hierro said at a news conference on Tuesday that the full-back is available for selection after training for the past week.
However, the Iberians struggled to break down a reshuffled Iranian defence that included Majid Hosseini in place of the injured Roozbeh Cheshmi.
Andres Iniesta, Spain's star midfielder, echoed Hierro's words, saying that the team are more than ready to go forward.
- Diego Costa has scored eight goals in his last eight global starts for Spain - he scored with both of his shots on target in their 3-3 draw with Portugal. It was a defense-first game, with only a single goal scored throughout.
Iran continued to have the better of the efforts as the half wore on, with Mehdi Taremi missing two glorious chances.
"Iran are a strong team and it's very tough to score against them".
Iran initially set out to sit deep and play on the counter but were forced to change their tactics after Spain scored.
But, with three points already in the bag, is it impossible?
With a photo of Spain's passing map from the first half of the match against Iran, accompanied by a photo of del Bosque, the post pointed out the uncanny resemblance between the two.
"It was very hard for everyone, but we have three points, that's what matters", Hierro said.
"In this moment we are more concerned because one member of our staff in difficulty from health point of view after VAR decision", Querioz told The Independent.
"The match the other day was not easy but I think the team has shown we know what we are doing and we trust what we are doing".
Football - an unsurpassed game of 90 minutes, which draws the line between euphoria and melancholy, encapsulates more than just entertainment.
"But congratulations to Fernando Hierro and Spain".
"We are only on the bench and we try to do as little as possible during the game". Everything is still open. "We're still alive and dreaming".
Following the match, nearly all Iranian fans were pleased with Team Melli's great performance, and were even saddened by the loss, which was not that much surprising.
Another chance came and went some 20 minutes later, when Vahid Amiri brilliantly nutmegged Gerard Pique and sent in a cross from the left to find Taremi in the box.
Defending on the number of forwards Hierro chhoses, Spain's midfield may rotate in a three or four-man central players.
Despite facing some difficulties initially, the fans were allowed to enter the stadium to witness the national team take on the European giants La Roja on Wednesday at the Kazan Arena. The Iranians will need to beat Portugal to advance. Queiroz against his old team... great game in prospect!