(CNN) -- There are football rivalries and then there is the rivalry between Iran and Iraq.
The two teams meet in Group D of the 2011 Asian Cup in Qatar, in what will be the most fiercely contested match of the group stage.
The two countries share a border and a bloody recent history, including an attritional eight-year war in the 1980s that is believed to have claimed the lives of up to a million people. Unsurprisingly, when the two meet on the football pitch, the results can be explosive.
"It's considered a derby game, just as (a match with Saudi Arabia) is considered a derby," Younis Mahmoud, Iraq's captain and star striker, told CNN after the team had finished training at the Al Gharafa stadium in Doha.
"There were also problems between us and Iran and years of war. So I think it is considered a derby and also a challenge."
This is something of an understatement. The two haven't played each other on home soil for decades thanks to the almost continuous political instability in both countries over the past 30 years. When the two do meet, in neutral venues, it becomes more than just a football match.
Take 2007, when both teams reached the final of the West Asian Championship in the Jordanian capital Amman, a warm-up regional tournament before the Asian Cup.
Thousands of Iraqis had fled to Jordan following the Gulf conflict so consequently the stadium was full of these refugees -- men, women and children -- from across the country, representing every sectarian group: Sunni, Shia, Kurd and Turkmen.
Almost every member of the team had lost family members due to the violence, and almost all had fled the country amid a raging insurgency.
There was also the threat from criminal gangs who increasingly looked to kidnap and extort money from the families of players.
"I probably have the hardest job in the world as I have to deal with these boys with many problems," the team's former coach, Brazilian Jorvan Vieira said before the tournament. Vieira had already lost his physio before the first game; he was killed in a Baghdad suicide bombing as he walked to a travel agent to pick up his ticket for Amman.
And just before the 2007 game with Iran, the entire Iraqi Olympic Taekwondo team, kidnapped months before, were found buried in a shallow grave on the road to Jordan.
A minute's silence was held in their honor.
Iran went on to win 2-1, fired up after Iraq's fans mercilessly booed the national anthem and chanted anti-Iranian songs. In defeat the Iraqi players were devastated. Younis Mahmoud removed his jersey, revealing the map of Iraq tattooed on to his left bicep, and congratulated the fans before thousands spilled out into the Amman night singing and banging their drums.
"Do you want to know what they are saying?" shouted Salif, a 16-year-old from Baghdad. "The Sunni and Shia are brothers. We will never sell Iraq [to Iran]."
Few could have imagined then what was to follow. Iraq won the 2007 Asian Cup, but not without tragedy. As fans celebrated the team's semi-final victory over South Korea, a suicide bomber blew himself up outside an ice cream stand in Baghdad, killing dozens of innocent football fans.
The team, devastated and weighed down with feeling of responsibility, considered quitting. But one woman's plea on national television, who held her dead son in her arms, convinced them to continue. From there on, Mahmoud believes, there was only ever going to be one victor.
"All our players wanted to take this cup because we saw on television one woman [whose] baby is dead. [She said] 'I need the players to take this cup ... because my son is dead'," Mahmoud recalled pitch side at the Al Gharafa training ground.
"I was fired for this game, I killed myself in that stadium to take this cup. Before we started the game [the 2007 final against Saudi Arabia] we had won. Because our heart was in this game. We killed ourselves to win this game."
Since then the Iraqi team has suffered a loss of form and plain bad luck. They were banned briefly by FIFA after a sectarian spat between the Sunni head of the Iraqi Football Association and the Shia-dominated Youth and Sports ministry, which tried to sack him. They failed to qualify for the 2010 World Cup and plunged 50 places on FIFA's rankings. But, Iraqi midfielder Nashat Akram believes the team needs to draw inspiration from the 2007 victory.
"The situation in 2007 was very bad. There was fighting on the streets. We won the Asian Cup and now that situation is gone," Akram told CNN.
"We don't have kidnap in our country any more. We have a very safe country."
On the pitch next door, oblivious to the presence of their rivals, flashbulbs from a dozen or so Iranian sports journalists pop as the Iran national team also arrive for training in the same complex. There are more than a dozen daily sports papers in Tehran alone, producing a football tabloid culture every bit as vociferous as that in England or Spain. And while Iraq can bask in the glory of being continental champions, the Iranian press has had little to cheer in recent years.
Since qualifying for the 2006 World Cup, Iranian football has been dogged by political scandal and poor results. The Football Federation Islamic Republic of Iran (FFIRI) was banned by FIFA after it emerged that the Iranian government had sacked the head of the football body, contravening FIFA's strict rule against political interference.
Recent Wikileaks cables also suggest that President Mahmoud Ahmadinejad personally fired former coach and Iranian legend Ali Daei after a string of poor results leading up to the 2010 World Cup.
The Iranian press crowd around Ali Kafashian, current president of the FFIRI, to get answers on how the team is preparing for the match against its neighbours. But Kafashian declines the opportunity to talk to CNN.
"You know the politics of talking to CNN, it's impossible," he said.
"It's dangerous!" shouted one of the Iranian journalists. And he should know. Iran is one of the most difficult countries to operate freely as a journalist, ranked 175th out of 178 countries on Reporters Without Borders' 2010 Press Freedom Index.
So it is surprising that the national coach, often jokingly referred to as Iran's most important job, is a naturalized American citizen. Afshin Ghotbi fled Iran as a young child after the 1979 Iranian revolution and built a career for himself as a coach in the U.S.
He was even selected as a scout for Team USA at the 1998 World Cup in France, to give the low down on the Iranian national team before the famous Iran versus USA match, which Iran won, prompting a million people to celebrate on the streets of Tehran. But in 2007 he returned to his country of birth, greeted at the airport by thousands of well wishers throwing flowers in his path. It was also the first time in nearly 30 years he had seen his mother.
Once training had finished, Ghotbi spoke openly about the importance of the rivalry between the two countries.
"You always have big rivalries like this with neighbours, take USA-Mexico, or Holland-Germany, Korea-Japan," he said, as the team filed onto the team bus painted the colors of the Iranian flag.
"There are a lot of beautiful rivalries in football that excite the fans. It is a rivalry. There's a long history of sports and politics. So my feeling is that it will be an exciting game. And I hope that energy from outside the game will be transferred to the pitch. It will be a spectacle."
However, this will be Ghotbi's last stint with the Iranian team. He will soon head to Japan to coach a club team there.
In cafes and houses either side of two countries' border, tens of millions will tune in for the stand-out tie of the Asian Cup so far. But progress in the competition will only be of passing interest. As is always the case between Iran and Iraq, the match will be much more important than that.