Nine qualifying groups in Europe, but only the eight best second-placed teams can reach the play-offs. Four teams, in two different groups, will fight for the last of those places. The remaining seven have already been taken.
The points managed against the bottom sides in each group are not taken into account when considering the best runners-up. This does not favour Bosnia, who have eight points to their name without considering those earned against Gibraltar.
The Bosnians can claim a maximum of 11 points, so it seems unlikely they will be the best second-placed team.
A slightly easier task for Scotland, who are currently eighth. By beating Slovenia, they will be through, but in case of a draw, they will have to pray for Slovakia to lose against Malta. The Slovakians aren't guaranteed a place by winning, as they need Scotland not to win.
It's not particularly easy for Slovenia. They have to beat Scotland and hope for Slovakia to be defeated at the hands of Malta, who are yet to win a match in their qualification campaign.
However, nothing quite as fantastical as what Bosnia are hoping for. The Balkan side are compelled to beat Estonia, while Greece have to lose at home against Gibraltar. The Bosnians will also have to hope Slovenia don't beat Malta and Scotland are defeated by Slovakia. Aside from that series of unlikely events, they must also win by a three goals more than those scored by Slovenia.
Lasty, if they overcome Cyprus, Greece can also become one of the best runners-up.