Spain will end their Group B campaign against eliminated Morocco on Monday, while Iran face Portugal, where only a win would be enough to secure them a place in the round of 16.
Kick-off is 7pm Nigerian time.
The former champions could have started on a better note if they hadn't sacked their coach Julen Lopetegeui two days prior to World Cup opener against Portugal.
- Spain have been eliminated at the group stage in two of the last three World Cup tournaments in which they've failed to win their first match (1998 and 2014) - however, they won the tournament on the other occasion, doing so in 2010 despite losing their first match to Switzerland. It was not to be but, for Iran, this World Cup is nowhere near over yet.
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. Spain may be the favorite, but there's no reason Iran can't pull off an upset if they're able to disrupt the Spanish offense.More news: Messi misses penalty kick as Argentina held by Iceland
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Iran has the ball in the back of the net!
The result left Spain joint top of their group with Portugal on four points, with Iran close behind on three going into the third and final set of games.
Iran could have scored in the 80th minute but Mehdi Taremi's header went over the bar. That has only happened twice before in World Cup history. Their service includes Fox Sports 1, Fox and Telemundo (in most markets) so you can stream the game with English or Spanish commentary.
It came in fortunate fashion for Costa, who looked to turn onto an Andres Iniesta pass and saw Ramin Rezaeian's clearance cannon in off his shin. La Roja showed plenty of class in the game, keeping the ball well, however, mistakes in conceding the early penalty and the goalkeeping error from the usually solid David de Gea blotted an impressive performance.
He also had generous words for opposite number Carlos Queiroz, a master tactician who has made Iran an extremely hard nut to crack.
"It's a crucial match that will determine our World Cup destiny", said Isco.