French Finance Minister Christine Lagarde, whose country holds the Group of 20 presidency this year, has the difficult task of picking up the pieces of last November's G-20 summit of heads of state in Seoul, which ended without any meaningful agreement on how to defuse long-standing tensions over trade and currency imbalances.
Finding the right tools to measure these imbalances - which many economists say contributed to the world's financial meltdown and endanger a broad recovery - is the primary goal at the gathering of finance ministers and central bank governors, Lagarde says.
"What we want to achieve Friday and Saturday is to identify a list of indicators, measuring tools, that will allow us to identify imbalances, then the causes of these imbalances, so that we can propose methods to coordinate our economic policies," Lagarde said this week.
The current system, in which "China saves and exports, Europe consumes, the U.S. borrows and consumes," is "probably not a good model," Lagarde said.
The list of the indicators being discussed includes countries' trade deficits or surpluses, budget deficits and levels of debt. Inflation and national savings rates are also likely to be considered as part of the range of possible indicators.
Officials will not even get to the more difficult question of setting thresholds for these indicators. "That's the next step," Lagarde said. Finance ministers will meet several more times this year before France's G-20 presidency culminates with a heads of state summit in Cannes in November.
The even more controversial question of how to enforce any thresholds that leaders eventually sign up to is yet further off the agenda. "Name and shame" policies like those used in the fight against international tax havens would be one, albeit toothless, possibility.
Agreement on which indicators to take into account, would be seen as a minor victory in France's year-long campaign to use its G-20 presidency to push changes to international monetary system, in which surplus countries often pile up reserves in the form of U.S. dollars.
U.S. Treasury Secretary Timothy Geithner and Federal Reserve Chairman Ben Bernanke will meet counterparts from Britain, China, Russia as well as the heads of the International Monetary Fund, World Bank and the European Central Bank.
But the G-20's grand ambition of entrenching "strong, sustainable and balanced" economic growth may come undone by the widening divergences in their paths out of the worst global recession in 70 years.
The problem is that the indicators "are all quite controversial in their different ways because of course countries will argue that the structure of their economy varies and what may be a sustainable deficit for one country may not be sustainable for another," Lewis said.
Officials from around the world, gathering amid tight security, are also likely to push European policymakers to get a tighter grip around the continent's debt crisis, which has flared up again in recent weeks. Yields on Portuguese government bonds again hovered near euro-era highs Friday and most economists believe that an international bailout for the country - similar to those arranged for Greece and Ireland - is only a matter of time.
Embarassingly for host France, its own efforts to target deficit reduction were slammed by the country's top audit body on Thursday, just before the meeting's kickoff. The government's budget watchdog said France's deficit was aggravated last year by tax cuts, and that "ample" reforms are needed if the country is to achieve its own targets.
Another obstacle to agreement this weekend is the wide variation in how the G-20's members have rebounded from the meltdown. Developing economies such as China, Brazil and India are roaring ahead even as Europe plods ahead fitfully, while the United States' jobless recovery falls somewhere in between.
"The momentum is seeping away from the G-20," Lewis said.
"There was certainly movement in 2008-2009, but now that the global economy seems to be on a better track and for many of the G-20 members prosperity seems assured, why would they want to prejudice that by bringing in radical changes," Lewis said.
"On the whole they're fairly happy with life, indeed they have every reason to be," Lewis added, "so they're not really concerned with sorting out the problems of the advanced countries."