There is tight security in Athens ahead of German Chancellor Angela Merkel's first visit to Greece since the Euro crisis erupted almost three years ago.
Thousands of police will create a safety zone for Ms Merkel's meetings with conservative Prime Minister Antonis Samaras and President Carolos Papoulias, aiming to keep demonstrators at arm's length.
Some 7,000 officers backed by water cannon and a helicopter have been mobilised for the German chancellor's six hour visit.
The visit comes as Greece bids to pass cuts of 13bn euro (£10.5bn) in order to secure more bailout cash.
Ms Merkel had faced criticism in Germany for failing to visit Athens thus far during the crisis, unlike EU President Herman Van Rompuy, European Commission president Jose Manuel Barroso and eurozone chief Jean-Claude Juncker.
The Chancellor's office has said she will convey a message of support for "ambitious" cuts already in place in Athens and encouragement to stay the course.
"She is going to Greece to express her support for the ambitious reform efforts that the Greeks have set out and are, in part, beginning to implement," Steffen Seibert told a news conference.
"We should not forget - and I think this is sometimes forgotten in Germany - that Greece can point to some successes when it comes to reducing the deficit through very difficult measures," added the spokesman.
Mr Samaras will greet Ms Merkel at Athens airport and the two will hold talks before the German leader meets President Papoulias.
Leftist and Communist-affiliated unions are holding separate protests and a three hour strike has been called in Athens from midday onwards.
The police declared a ban on "public gatherings and demonstrations" in a broad section of the city centre that includes the German embassy, parliament and the offices of government but the union gatherings lie outside this area and will be held as planned.
Ms Merkel's route from the airport is also off-bounds.
The German leader is a popular hate figure in Greece, often blamed for harsh austerity measures imposed by the Government in return for vital international aid, and has in the past been depicted as Adolf Hitler in tabloid caricatures.
Mr Samaras has assured Ms Merkel that she will be "welcomed in the appropriate way for the leader of a major power and a friendly country", but many in Greece object to the visit.
"(Merkel) is coming to rescue a corrupt and discredited political system that is subject to her interests," said Alexis Tsipras, leader of radical leftwing opposition party Syriza that is taking a leading role in the protests.