Iran began their campaign with a 1-0 win against Morocco but Queiroz has admitted they will have to produce their "best game ever" if they are to fulfil their aim of causing an almighty World Cup upset.
The expectation that they would play well back was unfounded, however, even if they kept their shape superbly, restricting Spain to a handful of chances in the first half.
Iran thought they had equalised soon after though, with Saeid Ezatolahi blasting home from close range, only for VAR to correctly chalk it off for offside.
Spain could not managed to get a second despite their best efforts while Iran nearly scored an equaliser when Mehdi's powerful header hit the crossbar.
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78th minute, THROUGH PASS: Collects the ball with plenty of space down the left and finds Costa with a delicious ball around the corner of the Iran defence.
"But this was our first match point, if we compare this to tennis, our second match point comes against Portugal". Whose side are you as the Spaniards take on the Iranians?
"We were not lying yesterday when we said in the press conference Iran is a tough team", said Spain coach Fernando Hierro, who replaced the sacked Julen Lopetegui only two days before their opening match against Portugal.
Costa got so frustrated with Iran's defensive tactics that he approached Beiranvand and provocatively stepped on his toes, leaving the 'keeper in visible pain.
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The pressure eventually took its toll as Diego Costa found the back of the net, albeit with the luck of deflection to put his side 1-0 up on 54 minutes.
While only one of them was a clear-cut opportunity Silva dropped deeper after the break and looked to gather the ball further away from goal.
David Silva has had the best chance of the game: swivelling 10 yards out but skying his volley over the bar.
Which channels will show FIFA World Cup 2018 Match-20 between Iran vs Spain coverage?
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