Argentina looked destined to exit the World Cup at the group stage for the first time since 2002 after their embarrassing 3-0 defeat to Croatia.
However, Nigeria's 2-0 victory over Iceland has blown Group D wide open, and keeps the World Cup dreams alive for Lionel Messi, Sergio Aguero and their team-mates.
After two games, Nigeria have three points, while Argentina and Iceland both have one. Leaders Croatia, on six, have reached the last 16 with a match to spare.
Crucially, Iceland's goal difference is marginally better than Argentina's - minus two, while the South Americans are on minus three.
Goal difference is the primary decider of group ranking at the World Cup, after points, unlike in the Champions League where head-to-head takes precedence.
The final games in the group kick-off at 7pm UK time on Tuesday, with Argentina playing Nigeria in St Petersburg, while Iceland face Croatia in Rostov.
Argentina must win their match, and at the same time better Iceland's result against a Croatian team who may rest players, given their knockout spot is secure.
So for example, if Argentina win 3-0 and Iceland win 1-0, then Argentina qualify on goal difference. If they win 2-0 and Iceland win 1-0, then Argentina would also go through - both sides would have four points and minus one goal difference, but Messi and Co would have scored three goals to Iceland's two.
Of course, if Iceland draw or lose and Argentina win, then Messi's hopes of being a world champion can continue.
However if both sides win 1-0, then Iceland knock Argentina out, as their goal difference would be minus one to Argentina's minus two.Iceland therefore require not only a win and for Argentina to beat Nigeria, but for the Argentina winning margin to be the same or narrower than theirs.
Nigeria meanwhile will progress if they beat Argentina, or if they draw and Iceland fail to win by more than two clear goals.
Nigeria would also be likely to progress with a high scoring draw, regardless of the Iceland result, as number of goals in all group matches follows goal difference in deciding the rankings.
So, should Nigeria draw 2-2 and Iceland win 2-0, for example, they would have the same number of points and goal differences of zero - but Nigeria would have scored four goals to Iceland's three, and would progress.
Courtesy: