David de Gea said he had the support of his Spain team-mates after he made an uncharacteristic error in Spain's 3-3 draw against Portugal at the World Cup.
The Premier League Golden Glove winner failed to save Cristiano Ronaldo's shot from long range moments before half-time on Friday, giving Portugal the ascendency in Sochi.
"The mister [interim coach Fernando Hierro] is with me and the whole team, so I am calm," he said.
"It's a mistake, a difficult ball, [but we] continue training to do things well in an important game against Iran because we have strong options to win.
"We deserved more but football is like that, it can happen to you, only those of us who put on our gloves and go out in the field know how hard [it is]."
Iran, who top Group B, are Spain's next opponents in Kazan on Wednesday.
