With oil prices in free fall and diplomatic crises raising the threat of more Western sanctions, Russian President Vladimir Putin and Crown Prince Mohammad bin Salman are planning to meet on sidelines of the G-20 summit later this week, Bloomberg reports. Even if President Trump snubbed Salman, and threatened to snub Putin, energy traders will be watching closely as the two leaders meet for the first time since both countries started pumping oil at the fastest pace since the 2016 OPEC+ production cuts.

Specifically, traders will watching for any indication of what both countries, which have formed an alliance allowing them to exert unrivaled influence over global oil markets (though producers in the Texas oil patch are struggling to change that), have planned for a meeting of the OPEC+ nations set for the following week in Vienna.

As one energy analyst told CNBC, the OPEC+ meeting could turn into a formality if the two leaders decide on a new course for the cartel and its allies.

The heads of the world's 20 largest economies are due to arrive in the Argentinian capital this weekend, where leaders will try to build a consensus on key issues. It comes a week before a much-anticipated meeting between OPEC and non-OPEC producers in Vienna, Austria, on December 6. "All eyes are now on the upcoming OPEC meeting, but the get-together could easily turn out to be a formality," Tamas Varga, senior analyst at PVM Oil Associates, said in a research note published Tuesday.

The meeting between the two leaders is happening at a critical time for both Russia and KSA. They are struggling to defend their share of the global oil market from producers in the Texas oil patch. Meanwhile, falling oil prices - Brent crude futures for delivery next month traded below $60 a barrel on Wednesday - are putting pressure on both countries' budgets. Though Putin has repeatedly brushed off these concerns, saying Wednesday that Russia is "fine" with oil prices at $60 a barrel, not long after he said something similar about oil at $70.

Though MbS could risk arrest on 'war crime' charges as soon as he steps off his plane, the Khashoggi scandal and the international backlash against what's seen as MbS's heavy handed rule likely won't factor into discussions between the two leaders.

But any discussion of oil prices between the two leaders will be hindered by the fact that Trump might not meet with either of them during the summit, sensitive about the scandals encircling both leaders, whom he has taken pains to defend in the face of a mounting public backlash. After all, the three leaders have become part of a triumvirate that, should they choose to work together, could effectively dictate prices in global oil markets.

Then again, while Trump has threatened to cancel his meeting with Putin, and has no plans to meet with MbS, traders can't rule out the possibility that the three could gather for a 'casual' chat on the sidelines of the summit.

And given the ramp in US shale production, the three would have plenty to discuss.