Greece's new anti-austerity government failed to secure an agreement to renegotiate the terms of the bailout programme in marathon talks between eurozone finance ministers Wednesday night, meaning the issue will go to the wire next Monday.
Tsipras will use Thursday's summit to show the other 27 European Union leaders his austerity-light replacement plan for Greece's 240-billion-euro EU-IMF bailout, which expires at the end of February.
"I am very confident that all together we can find a mutually viable solution, in order to heal the wounds of austerity and to tackle the humanitarian crisis across the European Union," Tsipras, wearing a silk scarf and heavy coat, told journalists as he arrived for the talks.
The start of the summit was delayed by three hours after Merkel and French President Francois Hollande stayed through the night in Minsk to seal a peace deal to end the Ukraine conflict.
Powerful Germany is the stiffest opponent of the plans unveiled by Tsipras, whose hard-left Syriza party won elections in January on the back of huge popular discontent with years of austerity.
Greece refuses to extend its current bailout, but failure to agree a new deal means Athens could default and then almost certainly crash out of the 19-country eurozone.
"Europe is always geared to compromise... And Germany is ready for that. Nevertheless one has to say that Europe's credibility is based on sticking to the rules and that we are reliable," she said.
"Now we will look which proposals Greece will make. Finance ministers will talk about it next Monday, we still have some days time."
World markets have been on tenterhooks over the outcome of the bailout row, fearing a catastrophic exit by Greece from the euro, but European stocks rose today with traders confident that a deal was still possible.
