Group D, which many regard as the tightest in the FIFA Futsal World Championship Chinese Taipei 2004, ended with a comfortable 4-0 win for Portugal in the opening fixture.
Orlando Duarte, whose team earned the bronze medal in the Guatemala 2000, felt they owed the result to teamwork, "Iran's best quality was also their worst - they were dependent on Vahid Shamsaee. He is a great player, but we prepared for him and played as a team."
The Iranians, semi-finalists at Hong Kong 1992, had arrived with high hopes after seven conclusive victories at the AFC qualifiers. The knew the first stage would be difficult - their coach Mohammad Ansarifard feeling that "Group D was the most evenly balanced".
The Asian Champions started with an experienced five - the youngest was 29-years-old. Shamsaee, scorer of 33 goals in 7 Asian qualification games and a hat-trick against a full strength Brazil side in a 4-4 draw, began up front with influential skipper Mohammed Reze Heidarian in defence.
In a cagey opening, Portugal had the lion's share of possession, but gradually Iran settled with danger man Shamsaee and Babek Masoumi bringing sharp saves out of Joao Benedito in the Portuguese goal. The power and movement of Shamsaee was a threat throughout but as the match wore on he was increasingly held in check by the Portuguese defence.
The energetic Luis Silva broke the deadlock on nine minutes, slipping between Shamsaee and Mohammad Hashemzadeh to drive home from just outside the area. Portugal doubled their lead when Ivan, the most effective player, jinked into space and released the Belgium-based Leo who lashed in across Reza Nasseri.
In between the goals, Siamek Dadashi and Farhad Fakhim were yellow carded - joined later in the book by Amir Hanifi as the Iranian's lost a little discipline.
Iran pressed throughout the second half but they could not beat Benedito. The Portuguese wrapped up the game with goals from Leo, who took a Goncalo pass before dancing through the defence, and a smart finish on the volley from Zezito.
While the defeat is obviously a setback, coach Mohammad Ansarifard is still positive, "I hope we can qualify from this group. I am sure we will play better in the next match."
Portugal's Duarte wasn't getting carried away: "This was a good result but nothing is decided yet. We have to be careful and take it step by step. Our expectations were to win today whether it would be 1-0 or 4-0."