HEDGE-FUND managers, commodities traders, ex-spooks and hacks all converge on Vienna on November 30th for the annual jamboree of OPEC, the oil producer’s cartel. Such attention may seem a little misplaced. During a year of schisms and mistrust, OPEC has repeatedly wrong-footed the markets and its credibility is in tatters. But the meeting promises to be a spectacle of brinkmanship that has oil markets on tenterhooks. At stake is not only the future of OPEC. The influence of Saudi Arabia, its biggest producer, is in play too. The kingdom, which triggered the collapse in oil prices exactly two years ago by stifling OPEC’s efforts to rig the market, finds itself backed into a corner by its arch-rival, Iran, undermined by Iraq, and increasingly hostage to the vagaries of Russia’s foreign policy. How did it get into this bind? More to the point, can it get out of it?

To understand what is at stake, go back two months to the decisive action of OPEC ministers in Algiers. After nine months of failed attempts to agree on a production freeze, they announced a collective output cut to 32.5m-33m barrels a day, as much as 1.1m b/d below current levels. That set off a rally in oil prices, even though ministers had left the hardest part until today's meeting: deciding how much of a cut each country should make. Since the meeting in Algiers, Iran has claimed it should be allowed to raise production to levels prior to the imposition of (now-lifted) nuclear sanctions. Iraq has quibbled over the level of production it should cut from. Russia, meanwhile, has been indecisive. It is not a part of OPEC, but Saudi Arabia wants it to participate to prevent it stealing market share. As a result, the oil price rally in September quickly went into reverse. Failure to make good on the promise in Algiers could push crude well below $40 a barrel.

That strengthens Saudi Arabia’s position. It hopes Iran, Iraq and Russia will subscribe to a deal given that a renewed slide in oil prices will further damage their economies. They are producing close to their full capacity, so a cut should be relatively easy to bear. What is more, Iran faces the threat of renewed American sanctions if Donald Trump, America’s president-elect, tears up the nuclear deal. That may make it keener to recoup higher oil prices while it can.

Yet this has become a game of geopolitics more than economics, and it will probably be decided only when the oil ministers of Saudi Arabia and Iran look each other in the eye to see if either blinks first. If there is a deal, the oil price will probably shoot higher; it would catch the market unawares, as it did in Algiers. If there is no deal, Saudi Arabia will probably fare worse than Iran, however much the latter is to blame. The oil markets would give up trusting OPEC. They would lose faith in the kingdom’s ability to forge consensus on oil. Lower oil prices would make it harder to part-privatise Saudi Aramco, the state oil company, undermining a key reform plank of Muhammad bin Salman, the deputy crown prince. Indeed, the outlook would be so bleak, there would probably be a fudge, with all sides committing to continue talking however far apart they are. Just don't expect the oil markets to buy that one again.