In November 2008, countries representing four fifths of the world's economic output came together to forge a collective front against the financial panic then engulfing the West.
More and more farms in Trump's political Midwest heartland are declaring bankruptcy, as China's retaliatory tariffs against US grain imports begin to bite.
The G7 has a stronger focus on politics in industrialised countries, including discussions on health, energy, environment and terrorism, while the G20 looks at economic issues facing developed and emerging economies.
The EU and US suspended potential auto tariffs in a truce announced over the summer, but that deal may not hold much longer, some observers predict.
Thomas Wright, a senior fellow at the Brookings Institution in Washington, said "there's a deep division in this G20 now between democracies and authoritarians".
"The last summits have been somewhat disappointing and marked by contention, particularly over trade-related issues". Trump's "America First" stance has already upended other recent world summits such as the G7 and the Asia-Pacific bloc APEC.
The weekend summit is confronted with increasingly dire warnings by the International Monetary Fund (IMF), among others, of the potential harm faced by the world economy from the tussle between top economies of the world. European markets and USA futures also gained.
Mr Trump was still scheduled to meet with Chinese president Xi Jinping, but analysts were not optimistic about prospects for a major breakthrough on the two countries' trade disputes a month before USA tariffs on Chinese goods are set to ramp up.
"I really don't know, but I will tell you that I think China wants to make a deal", he continued.
In a tweet on Thursday, however, Trump said, "Billions of Dollars are pouring into the coffers of the United States of America because of the Tariffs being charged to China, and there is a long way to go".
Meanwhile the US, Canada and Mexico are expected on Friday to sign a revamped version of the North American trade pact NAFTA, which Trump excoriated when running for president.
Trump also says he "probably" will meet with Russian President Vladimir Putin despite earlier threatening to cancel their sit-down. "That will be very determinative".
"If we do not show concrete progress, our worldwide meetings become useless and even counterproductive", he said. The exact location of the Ukrainian ships when they were boarded is subject to dispute.
Beijing has shown, in its grabbing control of the South China Sea and its establishment of naval outposts in the Indian Ocean, that it knows how to extend its empire while keeping the USA off-balance. "What's happening in the Sea of Azov is serious", said Francois Heisbourg, special adviser at the Foundation for Strategic Research in Paris.
It is likely to be to the fore of the meeting of European leaders called by Macron, along with demands to resist the trade protectionism now stalking the world economy 10 years after the first G20 summit was held in the throes of financial crisis.
Asked if China was seeking to prevent more United States tariffs at the high-stakes meeting, the ministry's spokesman, Gao Feng, said economic teams from both sides were in contact to implement a "consensus" reached by Mr Trump and Mr Xi in a phone call this month.
But an Argentine advertising company refused to erect the poster, Emine Dzhaparova, Ukraine's deputy information minister, said in Buenos Aires.