Iran head into their encounter with 2010 World Cup winners Spain on Wednesday holding the slender advantage in Group B after recording a narrow victory over Morocco.
Spain will take the positives from the 3-3 draw with Portugal but boss Fernando Hierro will want to see improvements in defence after witnessing Cristiano Ronaldo net a hat-trick in Sochi.
Iran
Iran have not made a habit of winning matches at a World Cup so when Morocco's Aziz Bouhaddouz put through his own net in the fifth minute of added-on time last week, it sparked ecstasy in the stands and back home.
The Asian nation went into this tournament having prevailed in just one of their previous 12 fixtures on the biggest stage, and seven matches had passed since their famous 2-1 triumph over the United States back in 1998.
However, in the short-term at least, the importance of that success has been surpassed by their achievement in St Petersburg, and Carlos Queiroz and his squad now have something to work with over the next 180 minutes of football.
Spain and Portugal are still favourites to progress through to the last 16 but the six-goal thriller between the two European giants has effectively provided Iran with two shots at getting the result that they require to break new ground at the World Cup.
Those associated with Iran will not get carried away - they were second best against Morocco and they only scored through a fortuitous goal - but Iran came through qualifying without losing a match and they will believe that they can do enough to avoid a defeat in the next two games.
Sardar Azmoun - known as 'The Iranian Messi' - will get his opportunity to showcase his talent against one of the best defences in the world, but it will take a team effort to get anything out of a Spain side further motivated after failing to gain victory on matchday one.
We are yet to see whether the inside knowledge of Queiroz will have any effect on his squad, with the 65-year-old having previously worked in Spain and coached the Portugal national team.
That said, when all is said and done, it will take a united performance on the pitch for Iran to cause one of the great World Cup shocks, but do not write off a team who will not be overawed by the tests which await them.
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Spain
Given the upheaval in the dugout ahead of the opening clash with Portugal, Spain will not be too disappointed with sharing the spoils with one of their biggest rivals but the manner of the performance may create alarm bells within the camp.
Both teams had their moments in Friday's game, but Spain contributed to their own downfall with mistakes leading to two of Portugal's goals - three if you include Gerard Pique's foul on the edge of the box during the closing stages.
No goalkeeper in the world would have saved Ronaldo's mesmerising strike into the top corner, but attention is coming David de Gea's way due to his error for the second, with the Manchester United stopper letting Ronaldo's shot go through his fingers.
De Gea has openly stated that he does not believe that he has received the necessary backing from the team's fans, but his latest mistake comes just days after one made in the friendly with Switzerland.
At the other end of the pitch, Hierro will have been delighted with the contribution of Diego Costa, with the Atletico Madrid having not enjoyed a free-scoring end to the domestic campaign.
The 29-year-old's first goal - a powerful low finish which came from outmuscling the Portuguese defence - suggested that the former Chelsea man is beginning to rediscover his confidence and that can only bode well for a team more known for their attractive football.
Drawing with Portugal means that there is still work to do for Spain - regardless of the opposition in front of them - but failing to prevail in their opening fixture may just sharpen their focus at a crucial time.
Based on last Friday's performance, expectancy levels have dropped to a certain extent but that may play into the hands of La Roja given their period in the spotlight.
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Team News
Hierro may decide against major changes to his Spain side in an attempt to establish some stability since Julen Lopetegui's exit.
Nacho netted a stunning goal against Portugal, but Dani Carvajal may come back into the team at right-back, while Saul Niguez may replace Koke in midfield.
As for Iran, Quieroz is unlikely to tinker with a winning team and that could see Ostersunds FK winger Saman Ghoddos kept in reserve.
Captain Masoud Shojaei should keep his place in the starting lineup, despite being withdrawn during the second half against Iran.
Iran possible starting lineup:
Beiranvand; Hajisafi, Cheshmi, Pouraliganji, Rezaeian; Shojaei, Ebrahimi; Amiri, Ansarifard, Jahanbaksh; Azmoun
Spain possible starting lineup:
De Gea; Carvajal, Pique, Ramos, Alba; Busquets, Koke; Iniesta, Silva, Isco; Costa
Head To Head
Wednesday's meeting in Kazan will represent the first ever clash between the two nations.
We say: Iran 0-4 Spain
Spain will hold respect for Iran due to their position in the group, but that may only lead to a more ruthless performance. Hierro's team will see themselves in a battle with Portugal regarding goal difference so expect a professional display on Wednesday.
