The Atlas Lions returned to the global showpiece since 1998 without conceding a goal or losing a game in their qualification group.
Despite the pairing with the European heavyweights, the 1998 African Footballer of the Year admitted that their encounter against Carlos Queiroz’s men at the Saint Petersburg Stadium on June 15 will be decisive for their progress to the next round.
"The first game will be our final," Hadji told BBCSport.
"It will be a tough game because we watched Iran in qualifying and they have a very good team and a very good spirit.
"But if we win, we have a great opportunity to reach the second round. That's what we are coming for.
"They are big nations of football [Spain and Portugal] and have won everything already.
"So that's why we have nothing to lose against these two. We have to play our football and fight - actually to give everything against them - because we know that it is not going to be easy, but we can surprise them.”