Greek voters may be about to plunge the European Union into a fully-fledged economic and political crisis. Opinion polls suggest the leftist, anti-austerity party Syriza is likely to emerge as the biggest party in Greece's late January election. If so the next Athens government may reject the terms of the bailout which is keeping the country afloat. And then what? Hardtalk speaks to Costas Lapavitsas, a London-based Greek economist who has been advising Syriza's leaders.