An unpredictable play-off stage will see eight countries fight for their place in the tournament, but four teams will have an advantage before the games kick off.
Switzerland, Italy, Croatia and Denmark have been seeded for the play-offs, meaning they will not face each other.
Their potential opponents will come out of a pool made up of Northern Ireland, Sweden, Ireland and Greece. These four teams will have to play the return fixture away from home.
The spotlight will mostly be on Italy who cannot afford to miss out on the World Cup. Always among the favourites to lift the trophy, their absence would be all but a disaster for the 'Azzurri'.