Iceland became the smallest nation to qualify for the World Cup after a remarkable few years, and the heroics of Euro 2016 proved that they can do it against some of the world's top sides.
They held Argentina in their opener, showcasing their qualities of spirit, work ethic and synergy, and represent a really tough test for Nigeria in the Super Eagles' second group game.
Their main player, Gylfi Sigurdsson, may only just be coming back from injury, but it's unlikely to faze Iceland too much.
How can Nigeria neutralise Iceland's strengths?
Iceland generally boast a very good defensive shape out of possession - two banks of four with two ahead.
There are good distances between units, they're compact, and they deny opponents time and space.
As a team, they are at times happy to sit deep and are confident in this approach.
Against this strategy, Nigeria will have to move the ball quickly, at a good tempo and get in forward areas early.
They must penetrate as well, as too often Argentina played in front of Iceland which they were comfortable with.
With only 22% possession, Iceland still got a draw out of the game, and had their own opportunities as they used the ball pretty well in offensive transition.
They had some good moments, and pounced on Argentina when they retrieved the ball. Nigeria cannot afford to give the ball away cheaply, particularly in deep areas.
As a team, they just keep going and play for each other with excellent work rate and mental strength. Nigeria will have to match their endeavour, and will need a big improvement after their debacle against Croatia.
Iceland's long throws into the box from Aron Einar Gunnarsson are a real weapon they can use to their advantage, this will come as a worry for the Super Eagles after they struggled with aerial balls into the box in their opener.
Also of concern, Iceland are a threat on set pieces and can use this to their advantage. Nigeria will have to be very organised, concentrated, and switched on when opposed against any set pieces, and Gernot Rohr will hope that his training drills are paying off.
Sigurdsson is a danger for Iceland, and Wilfred Ndidi must be at his best to silence the Everton man, who will drop off his striker in the hole and in between the lines to find good space.
He has excellent technical ability, and can link up play, see a pass or shoot from a distance.
You cannot afford to give him time and space, he has to be closed down and marked tightly.
How can Nigeria exploit Iceland's weaknesses?
Against Argentina, Iceland initially looked to apply pressure ahead when Willy Caballero had the ball and as he played out short from the back, both Sigurdsson and Alfred Finnbogason pushed further ahead looking to apply pressure.
As Iceland squeezed, Argentina kept the ball and moved it across the backline. With Iceland knowing they couldn't retrieve it early, they started to drop back into a medium-to-low block, with Argentina continuing to play at a slow pace and play sideways.
Nigeria must take the initiative at this situation and not ease off. If they can play it forward and directly, with players receiving well and in a position to get at the opposition, space can be exploited.
Iceland, while their Plan A is excellent, don't have much of a Plan B. If they don't have another approach and the original strategy isn't working, they can struggle.
They did have spells when they had the ball that they got forward as a team and committed players to the attack. When play breaks down in these moments, it is imperative that Nigeria move the ball quickly and get at them early with spaces to exploit.
Nigeria's attackers need to get on the ball and drive at the centre-backs, testing them with direct footwork.
The Super Eagles should mix it up and play sometimes to the forwards' feet, and sometimes down the channels. Too often Argentina didn't take the initiative, and Nigeria must not fall into a similar trap.
They must come out of the blocks firing with energy, with a good tempo, and get at Iceland, as playing slow and patiently will suit the Europeans. The longer the game goes on, they will grow into the contest and execute their gameplan, while will make life harder for Gernot Rohr's side.
When Iceland sit in and play narrowly, they can be hurt down the flanks.
Could Victor Moses - Nigeria's chief wide threat - have a big role to play in attacking the full-back?
Certainly, Argentina didn't exploit this potential weakness enough.
Conclusion
In Iceland's opening game they showed they were largely comfortable against a side dominating the ball, they just sat in deep, kept their shape and played on the counter.
Nigeria absolutely must lift the lethargic tempo they demonstrated in defeat by Croatia and do more than Argentina did to hurt their opponents.
The Europeans will be comfortable if the Super Eagles play with a pedestrian approach as they did in their opener, and it's imperative that the West African giants turn Iceland's backline and test them.