German commentators and business leaders warned Greeks on Monday that their creditors would not allow radical leftwing party Syriza's electoral triumph to back them into a corner in talks on Athens' massive debt.
Europe's top selling newspaper Bild called Syriza's platform "dangerous" for trying to reverse economic reforms championed by Germany, the paymaster of eurozone bailout packages.
"Sorry, Mr Tsipras, but that goes too far!" Bild warned, referring to Syriza leader Alexis Tsipras.
"The eurozone is not a gambling den where everyone can play as he likes," Bild fumed.
"A treaty is a treaty," it declared, saying that "Europe had upheld its end" of the deal since 2010 by providing "more than 200 billion euros" ($225 billion) to Greece.
News website Spiegel Online was more measured, saying it was possible to see Syriza's stunning victory as a "horror scenario".
But it said that "this vote could also go down in history" marking "the day when Greeks took their own destiny into their hands".
"Tsipras deserves a chance. Were the Greeks really supposed to vote for a party that has driven the country to its knees?" it said, referring to Prime Minister Antonis Samaras's conservative New Democracy party.
The conservative Frankfurter Allgemeine Zeitung called the result "the expression of the deep frustration of the electorate with the austerity policies of the last few years" as well as short-sighted actions of the established parties.
"But no matter what Tsipras has promised the Greek people, he can't avoid one truth: Greece needs more foreign money, either from the markets or from the EU," it said.
"He must choose between compromising with the troika or complete state bankruptcy, which would push Greece even more into the abyss."
The Federation of German Industry said Tsipras "must not undermine trust in Greece".
"Greece has made good progress on the path of reforms. It would be catastrophic to stop half way," managing director Markus Kerber said in a statement.
"These reforms are painful but correct... With good economic policies, Greece would have a good chance at significantly improving its lot."
However the giant German services union Verdi called for Greece to be given "a fair chance" to get back on its feet after a "disastrous austerity plan" and called the vote a "wake-up call for a shift in European policies".
"Greece needs space to breathe and the chance to make social and democratic reconstruction possible," the union's chief Frank Bsirske said in a statement.
"For that, it needs an investment programme to ease the worst suffering, the restoration of employee rights which were massively cut back during the crisis and firm action to fight corruption and tax evasion, particularly among the rich."
Julian Rappold, who analyses European politics at the German Council on Foreign Relations in Berlin, noted that it had "certainly not been a good week for" Merkel with the Greek vote and the European Central Bank's decision to launch a trillion-euro bond-buying programme.
"It's not very easy for the German government. They have to show signs of compromise -- no one wants to be the one who pushed Greece into the abyss," he told AFP.
"But I think the thing that is non-negotiable for the German government is the issue of debt forgiveness that Tsipras has raised."
The head of Germany's Bundesbank central bank, Jens Weidmann, underlined the point in an interview with public broadcaster ARD late Sunday.
"It is clear that Greece still needs the support of an aid programme and that of course also means that such a programme can only exist when promises are kept," he said.
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