At the first double-drumbeat the stadium suddenly goes hush; the "Hoo!" follows a split second later. Still a hush. It's like the first footstep of the T-Rex in Jurassic Park. Everyone is on edge. Then the next, about ten seconds later. Then another, a second faster; and so on until by the tenth it's rapid-fire. I counted 30 before it broke down into the general noise of a football crowd.
Iceland's fans - called Tolfan, for twelve, or "twelfth man" - debuted the Thunderclap at Euro 2016, the country's first major tournament. It was the perfect accompaniment to their magical journey through the Euros, in which they reached the semi-finals, and was replicated by the thousands who'd gathered at Reykjavik airport to welcome them back. It can be a bit intimidating at first, until you realise that the Iceland fans are known for their good nature - like the Roligans of Denmark from three decades ago.
Also, it's not really a Viking chant, which somewhat undermines the menace; Tolfan themselves say they took it from Scottish football, which in turn might have taken it from the film 300.
The Nigerian fans were a bit subdued in the first half, but the two goals clearly gave them the edge in the stands. Their response to the first thunderclap was "All we are saying, is give us a goal." When that duly happened, in the second half, they broke out into Oles. It's not the Thunderclap, but hey, it doesn't really matter what you sing when you're winning.
Little and large
How far Iceland will progress in the medium and longer term, once this current generation of players leaves the stage, is anyone's guess; the small population has been a boon in framing a centralized and structured approach to football. Size apart, the homogenous ethnic profile could also limit their growth; ethnic diversity gives teams different dimensions and different skills. That's something Belgium coach Roberto Martinez was excited about before taking up the job, and it's clearly been a factor in Germany's resurgence over the past decade.
Nigeria are at the other end; the world's seventh most populous country, with 500 ethnic groups linked together by Islam and Christianity, and with English as their common language (and the language of their national anthem). There are many lessons for India, for example, to learn from Nigerian football, which has been a leader in a strong footballing continent.
Their domestic football league is not in good shape, as the squad list suggests - only one of the 23 players play in the Nigerian league. But their strength is the range of the diaspora- their players ply their trade as far apart as England and China, Israel and Russia. That depth of global football knowledge comes in pretty handy in tournaments like this with so many variables, from the weather to the opposition.
Russia loves the World Cup
Today's attendance was 40904, which is good given these aren't the two most high-profile teams in this tournament, and Volgograd is not the most salubrious of destinations for the casual travelling fan. The Iceland fans were in predictably good number but Nigeria were the surprise; their support had a far greater distance to travel. There was a large number of locals at the ground; I could see carloads of Russians (rather, they were wearing Russia jerseys) headed to the ground when I was on my way. Attendance at the grounds through the tournament is said to be at 97%, which is a pretty impressive stat for any tournament.