Vladimir Putin has until the end of today to consider a one-off proposal from Petro Poroshenko, Ukraine’s embattled president, which could end the fighting in the Donbas and set a template for conflict-resolution elsewhere. Hoping to use their glaring personal animosity to save rather than end lives—and exploiting their nations’ shared love of martial sports—Mr Poroshenko suggests the breakaway region’s future be determined in single combat between the two presidents. Mr Putin’s spokesman has hinted he is amenable, providing the discipline is judo and that one of his associates gets the contract to build the venue. Officials from the OSCE will referee. Parties to other disputes are watching closely. Already Yanis Varoufakis, Greece’s finance minister, has floated the idea of settling the terms of its bail-out by arm-wrestling Angela Merkel and representatives of the “troika” of creditors on a tag-team basis. A spokesman for Mrs Merkel said: “Bring it on.”