The focus is back on Greek default concerns in the Eurozone crisis, and uncertainty on a deal to avoid default is expected to take a toll on global markets this week.

Greece debt talks are at an impasse and concerns are rising that the country will face a hard default within six weeks if a plan is not reached. Greek leaders are set to resume negotiations with private-sector creditors this week with hopes of reaching the base points of a debt deal to avoid national default by a Feb. 23 meeting of Eurozone finance ministers.

Talks in Greece broke down Friday with disagreements over the future interest rates Greece will pay. Greek Prime Minister Lucas Papademos said Monday, however, that a a debt swap deal will be done in time. He sent senior officials from the country to Washington to meet with International Monetary Fund officials, according to a report, hoping to ease fears and escalate plan resolve.

There is a little pause in these discussions. But I am confident that they will continue and we will reach an agreement that is mutually acceptable in time, said Papademos, according to a transcript of an interview with CNBC.

Bailout terms agreed to in October call for privately-held Greek debt to be cut in half. As a result, inspectors from the EU, IMF and ECB have said they must deal directly with the private sector to achieve that objective before more aid is given to Greece. The country needs a deal completed with the private sector of getting that done to avoid bankruptcy in late March when 14.5 billion euros ($18.37 billion) in bond resumptions come due, according to Reuters.

The bond matures on March 20, and without steps taken between now and then the country will be in default.

The U.S. markets are closed on Monday in observance of Martin Luther King Jr. Day. European stocks were slightly higher Monday after Standard & Poor's cut debt ratings of Italy, Spain, Portugal and Cyprus by two notches and France, Austria, Malta, Slovakia and Slovenia by one notch. The markets were apparently ready for the downgrades, however.

People were prepared for (the downgrades). As a result the reaction has been calm, which is good, said Andy Lynch, fund manager at Schroders, which manages 197 billion pounds, according to CNBC.

The threat of default by Greece is a larger concern.

At this stage, there is a growing risk of a coercive rather than voluntary debt restructuring, even though the latter is still our base case, said Joachim Fels, economist at Morgan Stanley, in an interview with Reuters.