Relations between Greece and independent South Slavic states (primarily Serbia) developed before the creation of Yugoslavia and played a prominent role during the Balkan Wars.

Serbo-Croatian (de facto state-wide) Slovene (in Slovenia) and Macedonian (in Macedonia) After the end of World War I, Greece perceived Belgrade as a powerful neighbor with potentially hegemonic tendencies in the Balkans.

[1] Yugoslav ability to attract support from the great powers, mainly France, created concerns in Athens that Yugoslavia would pressure Greece on the status of Slavic speakers of Greek Macedonia and potentially even the Port of Thessaloniki.

The Kingdom of Serbia reoriented its expansionist interest towards southern regions (with small number of ethnic Serbs) only after the Bosnian Crisis and in fear of encirclement by more powerful Austria-Hungary and Bulgaria.

The Yugoslav Non-Aligned policy enjoyed significant public support in Greece, especially among individuals and groups critical of too-close Greek alignment with the West.