Iran survived a spirited fight from Mauritania after Ali Naderi’s side had gone four goals up in the first period with Cheikh Belkheir’s hat-trick nearly forcing the match into extra-time.
Bicycle kicks from Ali Mirshekari and Movahed Mohammadpour put the Asian champion in control.
Belkheir pulled a goal back but Mahdi Shiri’s exquisite volley and Mohammad Ali Mokhtair’s free-kick made sure Iran went into the first break with a 4-1 lead.
Mokhtari added to the score early in the second period before Belkheir again reduced the deficit with Iran holding a 5-2 lead heading into the final period.
Mauritania seized the upper hand in the third period with Ahmedou Bilal’s strike before Belkheir's third goal with two minutes left to play made it a nervous ending for the Iranians, who ultimately hung on to claim maximum points.
Iran will meet Paraguay and Portugal in Group B on Saturday and Monday, respectively.