U.S. President Donald Trump announced ahead of the summit that he was canceling his meeting with Russian President Vladimir Putin over Russia's recent seizure of Ukrainian vessels.
But a senior Argentine official told The Associated Press later that the "adjective used by Sanders is too strong and doesn't reflect" Argentina's relationship with Beijing.
The officials weren't authorized to be named speaking about the closed-door discussions and spoke on condition of anonymity.
"There's some good signs, we'll see what happens", Trump said in Buenos Aires, where he was attending the G20 summit and was to have dinner with Xi on Saturday.
The two economic giants are locked in a trade war, which may possibly even escalate.
With a major United Nations meeting on climate change starting in Poland straight after the G20, United Nations chief Antonio Guterres said in Buenos Aires that "this is a make-it-or-break-it moment".
In contrast, Mr Putin and the crown prince shared a smiley, enthusiastic greeting at the gathering.
US President Donald Trump with UK Prime Minister Theresa May during a session titled Fair and Sustainable Future.
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"All issues being discussed at the summit have the same relevance", he told reporters.
Mr Trump described the US-Mexico-Canada Agreement (USMCA) - which replaces the Nafta free trade deal - as "probably the greatest trade deal ever". The President has openly expressed his fondness for hearing differing points of view on trade, and has fostered the intra-administration disputes that have marked his policy toward China.
Trump is expected to speak with several world leaders, including President Xi Jinping of China, at the summit, but his itinerary has already been streamlined, with Trump tweeting he was going to cancel a planned head-to-head with Russian President Vladimir Putin.
The bilaterals, however, are expected to take the center stage at this summit.
Earlier this month, officials from countries attending a major Asia-Pacific summit failed to issue a joint statement for the first time after the USA delegation clashed with China over trade and security.
As soon as he arrived, the crown prince was confronted by French President Emmanuel Macron, who pressed him on the Khashoggi investigation and the Saudi-backed war in Yemen.
Trade agreements should "move along with the economy", Pena Nieto said.
According to the International Monetary Fund, the South American nation is the only G20 member that would experience a decline in gross domestic product growth by -2.8 percent before the end of this year, Chilean newspaper La Tercera reported. But she will miss the summit's opening after her plane was forced to make an emergency landing in Cologne due to a technical problem.
The focus is on whether the G-20 countries can agree on a joint communique, as the United States and China, the world's two largest economies, have been engaged in tit-for-tat rounds of punitive tariffs on hundreds of billions of dollars of each other's imports.