Iago Aspas’ backheel in injury time was initially ruled out for offside before the technology correctly reversed its decision and gave Spain an equaliser, which combined with Portugal’s 1-1 draw with Iran, was enough to see La Roja win the group.
Hierro, a former defender for the national team, said that whilst the group games provided a good challenge, Spain must improve if they are to progress through the knockout rounds after twice coming from a goal down.
“I like the group, it was a level playing field, we weren't sure who was going to be first or second until the last minute and I have to admit we were lucky to finish first,” he said.
“We have to be very demanding with ourselves. This is not the way. We can’t allow the opposition so many chances. If we want to get to where we dream, we have to adjust these details and be self-critical, knowing there is room for improvement.”
VAR has been a big talking point in the World Cup so far, but Hierro was satisfied with how the technology has been implemented so far.
“All coaches and all players have been instructed about what VAR means and how it works,” he said.
“It has to be included and they’re going to try and use it as fairly as possible. We understood the referee was waiting for VAR and we did our job, the players didn’t pressure him.”
However, one of Hierro’s players, Thiago Alacantara was not convinced by the use of VAR.
“There are people who are in favour [of VAR], but for me it loses a little essence of football,” he said.
“But it is true that today it has favoured us.”
Spain will now face hosts Russia in Moscow on Sunday for a place in the last eight.