The teams finishing second, third and fourth qualify directly for Russia 2018, while the fifth-placed side go into a play-off against New Zealand.
Uruguay are assured the play-off place at worst and will qualify directly if they beat or draw with Bolivia at home. They may still advance even if they lose: only six of the 81 possible combinations of results would see them tied with their rivals, at which point the qualifying criteria would come into play to decide if they go through directly or have to take the play-off route.
Chile will be going to Russia if they beat Brazil away. So tight is the situation, however, that a draw or a defeat could see them qualify, go into the play-off with New Zealand or get knocked out altogether.
Colombia will go through if they beat Peru in Lima. They may still progress if they draw or lose, depending on results elsewhere.
Peru will go through if they beat Colombia at home and both Argentina and Chile fail to win. If all three win, then goal difference will decide who of Peru and Argentina goes straight to Russia and who plays New Zealand. If Peru draw, their chances of claiming a direct qualification place become remote. If they lose, the best they can hope for is the play-off place.
Argentina can qualify if they beat Ecuador in Quito, as long as Colombia and Chile do not both win. If they do, then La Albiceleste will be consigned to the play-off. Their chances of going straight to Russia drop to a mere 22 per cent if they draw. And if they lose, then they will only make the play-off if Peru also lose and Paraguay fail to win. Even then, it will all come down to goal difference.
Paraguay will definitely be going to the world finals if they beat Venezuela, Chile lose and Argentina fail to win. If they draw, La Albirroja will have only an 11-percent chance of making the play-off.
Article 20.6 of the Regulations outlines what should happen should two teams or more finish level on points in more detail. Who finishes above will be decided by prioritising each of these criteria in order:
Goal difference, Goals scored, Head-to-head points, Head-to-head goal difference, Head-to-head goals scored, Head-to-head away goals, Fair play points, Drawing of lots.