Morocco defender Aziz Bouhaddouz headed in an own goal in the fifth minute of stoppage time to give Iran a stunning 1-0 victory over Morocco in the first Group B game of the World Cup.
The rank outsiders in a group also containing Spain and Portugal were set for a hard-fought goalless draw of little use to either side until Ehsan Hajsafi curled in a free kick from the left wing.
Bouhaddouz launched himself at the ball, flashing a header past his own keeper Munir Mohamedi at the near post.
It was heartbreaking for Morocco, making their first finals appearance for 20 years.
The Iranians, whose only World Cup win previously was against the United States in 1998, celebrated as if they had won the tournament but they now have a chance to reach the last 16.
Morocco, who enjoyed more possession throughout, began in aggressive fashion, taking the game to their opponents and overloading their right flank as they targeted Hajsafi.
That approach almost paid off when Nordin Amrabat whipped in a dangerous cross from the right but Younes Belhanda's header from an acute angle flashed wide.
Iran were missing the calming influence of suspended holding midfielder Saeid Ezatolahi as Morocco over-ran them in the centre of the park with the clever Mbark Boussoufa directing play as the African side frequently attacked in numbers.
Morocco almost turned that initial pressure into a goal in the 19th minute when following a scramble in the area, Medhi Benatia's shot was well saved by Iran keeper Alireza Beiranvand.
Iran's Portuguese coach Carlos Quieroz had clearly given his side instructions to defend deep and look to break on the counter-attack and two minutes before the break that approach almost bore fruit.
Striker Sardar Azmoun broke clear though the middle but he shot straight at Mohamedi who got up quickly to keep out a follow-up effort from Alireza Jahanbakhsh.
Chances were at a premium after the break but a well-struck effort from Morocco's Hakim Ziyech brought out a fine save from Beiranvand nine minutes from the end.
