The top two teams in the group will face either England or Belgium. Nigeria captain John Obi Mikel has already warned Croatia to play their strongest side against Iceland.
Eight of the 32 teams have been eliminated, with the other 24 teams either battling for a place in the knockout stages or to see which team tops each group. A win versus Nigeria would give them a shot to advance but is hardly a give in.
With an initial six-group stage, the best four third-placed teams also progressed.
All ties are broken by a list of tiebreakers, first by goal differential, then (if still level) goals scored, goals scored against the tied teams, even down to the lowest number of disciplinary points (yellow and red cards). Australia aren't in the worst spot in that regard, but they still have to find a way through a proud nation in Peru who want to win a match at their first World Cup since 1982.
Advances with a win over Argentina. Australia must win to stand a chance, but surely fear that France and Denmark will play out a tepid draw like the Disgrace of Gijón. They've both got two each so far and if their records are still identical after the final group game, Germany will go through by virtue of the fact they beat Sweden 2-1 when the two sides met on Saturday night.
Argentina will qualify with victory over Nigeria coupled with Iceland failing to defeat Croatia. Heavy takes a look at all the groups standings, and will continue to update this as games go final.
Wins or draws for Brazil against Serbia and Switzerland against Costa Rica will send both through. A draw would require Spain to lose by at least two goals for Iran to advance.
Brazil and Switzerland are tied on points (four).
Serbia must beat Brazil to qualify but a draw could see them through if the Swiss are beaten by Costa Rica by more than one goal.
Japan sit in the box seat here, as they meet winless, hapless and eliminated Poland on Friday at 2am. They will also go through with any win should Sweden fail to beat Mexico. Meanwhile, a cloud hangs over the Egyptian team with Liverpool star Mohamed Salah reportedly telling Egypt team officials and teammates that he is considering retirement from worldwide play because he is angry about being used as a political symbol while the World Cup squad was based in Chechnya. Can also advance with a draw if Switzerland loses and Serbia has the better goal differential.
If Mexico and South Korea win, the three bottom teams would be tied. England needed an extra time goal from captain Harry Kane to see off Tunisia, but completely demolished Panama. Belgium now have three yellow cards to England's two, meaning this could be a battle of discipline more than anything.
Japan just need a draw against Poland on Thursday to guarantee progression, and they'll be joined in the next round by the victor of Colombia v Senegal. If Colombia, win Japan will need to lose by fewer goals than Senegal to progress.
Colombia will qualify with victory over Senegal.