Despite lenders' apparent readiness to give Greece more aid, the country's debt level is still a major bugbear. There are growing calls for a debt haircut to enable the country to return to growth, which not everyone is happy about.
Germany remains opposed to any such move, fearing it could set a precedent for other indebted euro nations. Schaeuble told Deutschlandfunk radio Thursday that a debt haircut would be incompatible with the country's membership of the euro.
Economist Christoph Schmidt agreed, telling CNBC that an outright debt haircut was "simply impossible."
However, in a meeting with the German and French finance ministers on Thursday, U.S. Treasury Secretary Jack Lew "underscored the importance of achieving debt sustainability in the upcoming negotiations," according to the Treasury Department.
Meanwhile, Christine Lagarde, managing director of the International Monetary Fund (IMF), told French radio on Friday that debt relief was needed to make the Greek agreement viable, Reuters reported. She said that a significant extension of Greek debt maturities and reimbursement deadlines could be enough, however.
Bob Parker, senior advisor at Credit Suisse, agreed, telling CNBC that there was no other option for Greece.
"Greece has debt in excess of 320 billion euros – that is close to 200 percent of GDP," he said.
"Yes, the maturities have been extended and interest rates have been cut, but unless Greece can get very serious access to capital markets, I think Christine Lagarde is absolutely right, over the long-term, there will be have to be haircuts and debt reductions for Greece."