Crashing oil prices brought Russia and Saudi Arabia closer together than ever. But now, a race to satisfy China's huge energy needs threatens to drive them apart.

Russia and Saudi Arabia have closely coordinated their efforts to eliminate a massive oil supply glut that sent crude prices crashing last year to unthinkably-low prices.

They agreed, along with other major producers, to slash their collective crude production as part of an effort to support prices. Last week, they extended the deal by an additional nine months.

The most recent sign of cooperation between the world's top two oil producers came this week, when Russian President Vladimir Putin met personally with Deputy Crown Prince Mohammed bin Salman to reinforce the agreement.

Behind the scenes, though, there is another reality: Saudi and Russia are engaged in an intense battle over who will be the top supplier to China, a major energy importer with an insatiable appetite for crude.

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