It is important to stress what this is not a vote for. It is not a vote for leaving the euro - a vast majority of Greeks continue to favour staying in the currency. Syriza's 40-year-old leader, Alexis Tsipras, has himself tried to avoid making too many headline-grabbing threats on the campaign trail. But the basic party platform will unquestionably lead the new government into a collision course with northern European governments, led by Germany. Northern Europe will not countenance even partial forgiveness of the troubled southern country's debts. And even measures that make debt easier to repay, such as easier interest rates and timings, will likely be seen as being dependent on continuing commitment by the Greek government to fiscal austerity. Mr Tsipras has ruled out exiting the euro; he has been similarly explicitly negative about default or unilateral
It is clear that the markets do not, as yet, see widespread disruption as likely. Although the yield on Greece's own 10-year treasury bonds rose 50 basis points to almost nine per cent, other vulnerable countries - such as Spain and Portugal - saw no disruption. Clearly, there is little concern about panic and contagion. However, most market participants will be bracing for volatility. As Mr Tsipras forms a government and begins the hard process of bargaining with a resolute northern Europe - led by Germany's chancellor, Angela Merkel - there are bound to be moments of brinkmanship. Every apparent crisis may not be a real crisis, but simply hard bargaining - but any one of those moments could destabilise markets that are already shaky for numerous other reasons.
The prospect of a Greek exit from the euro zone itself continues to be considered remote. Yet it is difficult to see how Syriza's demands and northern Europe's expectations can be reconciled. Europe's leaders and its financial institutions would be wise to at least start contingency planning for a prolonged uncertainty, if not for an orderly exit for Greece.