Portugal will be the next to restructure its debts in a manner similar to Greece, and both countries will likely exit the eurozone, says New York University economist Nouriel Roubini.
Greece recently restructured its debts with private creditors, and while the deal gives the country breathing room, it doesn't solve its economic problems of shrinking output and rising unemployment.
The only way out is through abandoning the euro, which would make the country's exports more competitive.
"Greece will be the first country to exit the eurozone, not this year but maybe later next year, but in order to restore growth, competitiveness and external balance they need the real depreciation," Roubini tells CNBC.
That would force Portugal to follow suit.
"In terms of debt restructuring after Greece, I think Portugal is the more likely that is going to require a debt restructuring and maybe eventually an exit like Greece," Roubini says.
Bond markets in the larger Italy and Spain have calmed lately as evidenced by falling yields on government debt — lower yields illustrate less fear on the part of lenders.
But things could change.
"The recession is becoming more severe, and you have fiscal austerity, you have the credit contraction and you have the strength of the euro, and if the recession doesn't bottom out, in a few months from now, the market is going to worry about the fiscal deficit, it's going to worry about growth and about unemployment, and then the spreads are going to widen again."
The European Union and the International Monetary Fund (IMF) recently set aside $172 billion in rescue funding for Greece but made restructuring its debt with private creditors a requirement.
"This is an important step that will dramatically reduce Greece's medium-term financing needs and contribute to debt sustainability," IMF managing director Christine Lagarde said of the private debt swap, according to the AFP newswire.
"The IMF's continued support would be part of an integrated package where all parties — the Greek government, its European partners, the private sector, and the Fund — would play their part to help the Greek people overcome this crisis and over time restore growth, contributing to broader global financial stability."