MATCH REPORT: Argentina 1 Iran 0
Lionel Messi's brilliance ended Iran's hopes of an unlikely point as Argentina booked their place in the second round.
The Barcelona man curled home a wonderful winner a minute into stoppage time to deny the underdogs in Belo Horizonte.
It was harsh on a spirited Iran side who had gone close through Charlton's Reza Ghoochannejhad and Fulham's Ashkan Dejagah, with both being denied by Argentine goalkeeper Sergio Romero.
Iran started on the front foot but Jalal Hosseini could not quite get enough contact on his header from Dejagah's free-kick and the ball trickled wide.
Iran were keeping plenty of players behind the ball and Angel di Maria, Messi and Sergio Aguero all saw attempts to break through closed down quickly.
Marcos Rojo should have put Argentina ahead moments later but headed Di Maria's corner wide of the far post before Ezequiel Garay headed over from six yards from Messi's free-kick.
But having survived the onslaught, it was Iran who came closest to breaking the deadlock five minutes before half-time.
Dejagah's corner was met by Hosseini but he was unable to keep his header down under pressure from two Argentine defenders.
Messi had been kept quiet for large periods of the first half but on 50 minutes he came to life, freeing himself from four Iranian defenders to feed Pablo Zabaleta but his left-footed shot was wild.
Moments later, Iran broke with real purpose for the first time in the game and Pejman Montazeri cross found Charlton striker Ghoochannejhad but his header was straight at Romero who saved well.
Iran then had a loud penalty shout turned down when Dejagah was brought down by Zabaleta in the box but referee Milorad Mazic said the right back had got a touch on the ball and waved away the appeals.
Argentina were at times playing with a 4-2-4 formation as they desperately searched for an opener but, despite a number of teasing crosses from the left by Rojo, no Argentine forwards were able to get on the end of them.
Iran were looking the more likely to score with a corner causing an almighty scramble in the Argentine box before Dejagah got ahead of Zabaleta to reach Montazeri's cross.
His header looked to be heading for the top corner but Romero stretched out a hand to tip it over for a corner.
Messi curled a free-kick into the side netting before Alireza Haghighi pushed a Rodrigo Palacio header for a corner while at the other end,
Romero was again called into action from Ghoochannejhad after the striker held off two defenders as Iran broke from an Argentine corner.
But Messi broke Iranian hearts in the first minute of injury time as he struck a magnificent effort from 20 yards, which curled beyond a full stretch Haghighi.
Argentina (4-3-3): Romero, Zabaleta, Garay, Fernandez, Rojo, Gago, Mascherano, Di Maria (Biglia 94), Aguero (Lavezzi 77), Messi, Higuain (Palacio 77) Subs not used: Orion, Campagnaro, Perez, Rodriguez, Fernandez, Demichelis, Alvarez, Basanta, Andujar.
Iran (4-5-1): Haghighi, Montazeri, Hosseini, Sadeqi, Pooladi, Shojaei (Heydari 76), Teymourian, Nekounam, Hajsafi (Haghighi 88), Dejagah (Jahanbakhsh 85), Ghoochannejhad Subs not used: Ahmadi, Ansarifard, Haddadifar, Mahini, Alenemeh, Rahmani, Beikzadeh, Beitashour, Davari.
