Spain beat Iran 1-0 at the Kazan Arena. Forward Diego Costa netted the winning goal in the 54th minute and was named the man of the match.

“We need to be patient and play calm in the match with Iran in order to score," Hierro said.

"The break helped us, we made corrections, took a look at ourselves and encouraged the boys. It was important to play a more expansive game, to move around more.

"The break was important psychologically. It was important to believe in ourselves, no matter how difficult the match was. Now we have four points and we can be content with ourselves."

Hierro also paid tribute to Costa, who has scored three times at the World Cup so far.

“(Costa) is a man who does not compromise, he is a fantastic player and can do even more. Diego Costa puts himself about, he works well with the ball,” he said.

Spain will face Morocco in the final Group B match on June 25, while Portugal will play Iran to determine which of the three teams advance to the knockout stage.

The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches being played in 11 cities across Russia.