Saudi Crown Prince Mohammed bin Salman arrived in Buenos Aires on Wednesday for the meeting of G20 leaders this weekend.
The crown prince's trip to Argentina follows a tour of Arab countries that included the UAE, Bahrain, Egypt and Tunisia.
Prince Mohammed and Russian President Vladimir Putin are expected to hold talks on the sidelines of the summit, according to people familiar with the plan.
Their meeting comes as Saudi Arabia is under international scrutiny over the killing of journalist Jamal Khashoggi and days before a crucial meeting of Opec and allied oil producers in Vienna. Saudi Arabia will try to persuade Russia to co-operate on curbing crude output next year following oil's plunge back into a bear market.
US President Donald Trump, who has built much of his Middle East strategy around an alliance with Saudi Arabia, has no plan for a one-on-one meeting with Prince Mohammed, the White House said on Tuesday.
But Prince Mohammed's meeting with Mr Putin will be closely watched in oil markets. Talks between the two leaders helped secure historic production cuts in 2016 that rescued prices from a multiyear slump.
Co-operation between Russia and Saudi Arabia has been "highly successful not only to stabilise oil prices but to build significant mutual trust and the mechanisms for further Opec co-ordination", said the chief executive of the state-run Russian Direct Investment Fund, Kirill Dmitriev, who will be taking part in talks with Saudi officials in Buenos Aires.
Russia and Saudi Arabia are de facto leaders of the alliance between the Organisation of Petroleum Exporting Countries’ and other oil exporters. After agreeing in June to boost output to offset supply losses from Iran and Venezuela, the countries now have different positions on whether action is needed to stem the price fall.
While Saudi Arabia has called for broad output cuts and warned of an emerging glut, Russia has stuck to a wait-and-see approach, saying further market monitoring is needed before any decision is taken.