Thousands of police have been put on guard in the centre of Athens for German chancellor Angela Merkel's first visit since the eurozone crisis began three years ago.
More than 7,000 officers have cordoned off huge areas to keep demonstrators away as Mrs Merkel holds talks with prime minister Antonis Samaras.
Her five-hour stop is seen by the government as a historic boost for the country's future in the euro, but by protesters as a harbinger of more austerity and hardship.
Many of Europe's leading politicians have avoided official travel to Greece and the risk of a hostile reception, as the debt-saddled country struggled to keep up with commitments needed to guarantee rescue loan payments and long-term euro membership.
But Mrs Merkel, heading Europe's largest bailout contributor, accepted Mr Samaras' invitation to Athens despite failure by his government so far to conclude a massive new austerity package.
After months of tough rhetoric, the chancellor may be preparing her own voters for a more tolerant approach toward Greece ahead of federal elections next year, according to Jason Manolopoulos, author of the 2011 book on Europe's financial crisis, "Greece's Odious Debt."
"Given how some other members of the (eurozone) core - Austria, Holland, Finland - had made some very harsh comments ... I think it does send a message to Greece," he said.
"But I think it's also important, if not more important, for German domestic consumption."
Mrs Merkel will meet Mr Samaras and president Karolos Papoulias, the largely ceremonial head of state, in adjacent buildings before flying back out of the country.
Draconian security measures include a ban on public gatherings outside the German Embassy and other parts of central Athens as well as within 100 yards of her motorcade route from the airport. Mr Samaras' own partners in his coalition government described the police measures as excessive. And Greece's main labour union, the GSEE, called them a "display of force ... aimed at cancelling our democratic rights" insisting it would go ahead with plans to stage a rally near parliament.