"Not a single day goes by without people stopping me in the street and thanking me for what we've achieved for their nation. I've worked in football for more than 20 years, across four continents, and this is among the most passionate football country I've seen," Gaspar said.

Yet when the initial call came from his long-time associate, Carlos Queiroz, it took Gaspar some time to consider his response.

Having worked with the former Real Madrid boss at Sporting, Japan's Nagoya Grampus and the South African and Portuguese national teams, Gaspar knew they had an unbreakable working relationship but with the offer on the table being to head to Iran as Queiroz's assistant there was a moment of reflection.

"I spoke with several people I know who'd worked in Iran, and of course with my family, and while there was a lot of negative news coverage around the country at that time I wanted to see things for myself," he said.

"Of course I have a wonderful personal and professional relationship with Carlos Queiroz and he is truly a wonderful coach; his leadership is unquestionable and his attention to detail both on and off the field is incredible – he puts his heart and soul into everything and that relationship helped with my decision."

"But I knew that we were talking about a nation which had undergone years of sanctions and isolation for political reasons but I thought maybe we could help, with football, to be a bridge between nations.

"I often say the best ambassador in the world is the game of football."

Now, almost three years after his arrival, Gaspar argues that the reality on the ground in Tehran is much different to how the nation is often portrayed in the western media.

"The country itself is much more multi-cultural than I expected; it's not a vast desert and there are four completely different seasons," Gaspar said.

"Even with me being an American I don't feel unsafe at all, I think ordinary people are just more curious than anything else."

"The food is delightful and the people here you realise are the same as anywhere else – they have bills to pay, they embrace their loved ones, they cry and they laugh."

Over the past few years the football loving folk of Iran – and there are a vast many – have been doing a lot more laughing than crying.

Karim Ansarifard scored after just four minutes in the pair's first competitive match - against the Maldives in the second round of World Cup qualification - and from there Iran breezed through the next stage undefeated across six matches.

The final section pitted Team Melli in a tough group containing Uzbekistan and Korea Republic and on the final matchday, away in Ulsan; Iran finally clinched qualification for the first time in eight years.

It was a huge breakthrough for the nation and came amidst the backdrop of both an acrimonious relationship with the Korean side and a ground-breaking election in Iran, where the moderate Hassan Rouhani was swept to power.

It was, as Gaspar recalls, a chaotic time.

"A couple of days before we qualified President Rouhani was elected and there was already quite a celebration from that and then when we reached the finals it was just an explosion of joy," he recalled.

"When we arrived back in Tehran it was chaos, there were thousands and thousands of fans waiting to greet us and we went straight to both (former President) Ahmadinejad's compound and President Rouhani's palace – both spoke of the joy that we had brought to Iranians."

Now though, with the tournament just a fortnight away there are many that are questioning what shape Team Melli will be in when they arrive in Brazil.

Economic sanctions have hit the country hard and football has not been exempt; a planned training camp in Portugal failed to materialise, the federation has struggled to attract top-tier nations for warm-up matches and there was a farcical situation last month when a host of domestic club sides refused to release players for a camp in South Africa.

Captain Javad Nekounam was particularly scathing.

Speaking to Iranian media he reflected: "None of the promises turned into reality. If we did not have good preparation until the matches start there shouldn't be any expectations. Whatever happens, the authorities must be held responsible for the results."

Gaspar though refused to concede that all hope is lost.

"We're in a group with Bosnia and Herzegovina, Nigeria and Argentina and certainly it's a tough selection but expectations here are high. The national team has never reached the second round and that's our aim and mission," he said.

"We know the hurdles are high but there will be 75 million people scratching on our backs waiting for it to happen."

The nucleus of the team is increasingly being drawn from beyond Iran's borders and on occasion not without controversy.

In the country's first finals appearance, in 1978, the entire squad was domestically based; in 1998 there were three foreign-based players and in 2006 there were seven - this time around that number is significantly larger.

Of the extended 30-man squad, 10 are drawn from leagues outside the country.

The captain, Javad Nekounam, is currently plying his trade in Kuwait while the attacking nucleus of the squad is European-based, led by Fulham's Ashkan Dejagah, Las Palmas's Masoud Shojaei and the jewel in the crown – former Dutch youth international Reza Ghoochannejhad.

The probable first choice goalkeeper, Daniel Davari, played in the Bundesliga with Eintracht Braunschweig but has since joined Swiss side Grasshopper while American-born, Canadian-based right-back Steven 'Mehrdad' Beitashour has suddenly rocketed into World Cup reckoning.

There are though a smattering of talented youngsters for whom Brazil could be a breakthrough tournament. The most prominent of the lot – and a name you'll be hearing a whole lot more of – is Sardar Azmoun. The 19 year-old forward has been a standout for Russian side Rubin Kazan this year and is reportedly being chased by a host of leading club sides.

Regardless of the final make-up of the squad not many judges rate Iran as much of a chance of progressing from the group stage but the one thing that Gaspar believes will aid Team Melli - and which sets it aside from many others - is a driving belief, bordering on obsession, to prove itself on the world stage.

"We know it's an extreme challenge in terms of this generation of players perhaps not being the best that the country has ever had but whereas in many countries – and many of those at the World Cup you'll see a lot of players who are doing it for the money I can honestly say that all these guys here play for their people not for the salaries or the fame," he said.

"When you see the derby in Tehran where there's 100,000 people clad in their colours chanting and singing you see what football means and anytime someone brings honour to their country, such as myself and Carlos have, the joy is expressed from the depths of their heart."

That's a way of life that resonates for Gaspar, the son of a former professional goalkeeper from Portugal who imbued his son with a love of the game from a young age.

"My dad was the one who I have to thank for this journey. Some of my earliest memories are of the training we used to do together, striking balls at a cement wall behind buildings or off trees in our local park," Gaspar said.

They were lessons not just in football, but in life.

"One day, when I was 15 or 16, he came to the park with a bag of balls and I didn't really react as we were practising. He asked me what was wrong and I told him that he couldn't beat me anymore," he recalled.

"He made me walk t10 miles home and that was the last day he trained me; it was such a strong lesson to learn at a young age but our bond endured through all these years."

Last year the American network CNN travelled to Tehran to record a profile on Gaspar and shortly after Iran's assistant coach had to return home as his father was seriously ill in hospital.

"I was sitting in the hospital with my dad, the man who started this journey for me, and the CNN story came on the TV," he said.

"He grabbed my hand, gave me a thumbs up and looked up at me with such pride."

Shortly after, less than a year before his son takes his place on the bench in Curitiba for Iran's opening match with Nigeria, his father Manuel passed away.

Now, Gaspar travels to Brazil with personal goals to honour his family, and his Iranian players with the hopes of a huge nation upon their shoulders.