Morocco didn't concede in six matches in African qualifying, while Iran kept nine straight clean sheets before letting in two goals in its final qualifier - by which time Carlos Queiroz's team was already guaranteed a place at a second straight World Cup.
Morocco have lost their first game at the 2018 World Cup in a very painful manner as a late own goal by substitute Aziz Bouhaddouz saw the Atlas Lions fall 1-0 to Iran.
The result marks Iran's second ever World Cup victory after a 2-1 win over the United States in France during the 1998 tournament. Enthusiastic Iranian women were among them.
"We train and we play under [bad] conditions", Queiroz said. I think it should be the exact opposite because 99 per cent of our boys, they buy the boots, so the statement should be in the opposite direction and they should thank them. They are just football players.
Iran suffered a what looked to be a devastating final blow, as Alizera Jahanbakhsh was stretchered off with just five minutes to play to seemingly sum up a fairly hard day.
Morocco coach Herve Renard confirmed he will be without winger Nabil Derar, who is making a gradual recovery from a calf injury.
The 2018 FIFA World Cup will be held from June 14, 2018 (6/14/18) until July 15, 2018 (7/15/2018) in Russian Federation.
With Spain and Portugal the other teams in Group B, Friday's (Saturday NZT) match in St Petersburg was regarded as a must-win game for the two outsiders.
Fans unfurled a protest banner at the stadium Friday in the Russian city of St. Petersburg during Iran's opening match against Morocco, prompting a brief commotion.