Despite the upbeat public statements, both nations are increasingly suspicious of each other, with the United States fearing that China has stepped up a timeline for seizing Taiwan.

US officials said ahead of the meeting that Biden hoped to set up "guardrails" in the relationship with China and to assess how to avoid "red lines" that could push the world's two largest economies into conflict.

The most sensitive issue is Taiwan, the self-governing democracy claimed by China.

The United States has been stepping up support for Taiwan, while China has ramped up its threats to seize control of the island. After House Speaker Nancy Pelosi visited Taipei in August, China reacted by staging unprecedented military drills.

On the eve of his talks with Xi, Biden met with Japanese prime minister Fumio Kishida and South Korean president Yoon Suk-yeol on the sidelines of a Southeast Asian summit in Cambodia, with the three leaders jointly calling for "peace and stability" on the Taiwan Strait.

Biden is also expected to push China to rein in ally North Korea after a record-breaking spate of missile tests has raised fears that Pyongyang will soon carry out its seventh nuclear test.

First in-person exchange

Xi is paying only his second overseas visit since the start of the Covid-19 pandemic and will meet a number of key leaders.

He will hold the first formal sitdown with an Australian leader since 2017, Prime Minister Anthony Albanese announced, following a concerted pressure campaign by Beijing against the close US ally.

Xi's last in-person meeting with a US president was in 2019 with Donald Trump, who along with Biden identified China as a top international concern and the only potential challenger to US primacy on the world stage.

And though the meeting is the first time Xi and Biden have met as presidents, the pair have an unusually long history together.

By Biden's estimation, he spent 67 hours as vice president in person with Xi including on a 2011 trip to China aimed at better understanding China's then-leader-in-waiting, and a 2017 meeting in the final days of Barack Obama's administration.

Since entering the White House, Biden has spoken virtually five times with Xi but told him Monday there was "no substitute" for face-to-face discussions.

Absent Putin

Though he is engaging Xi, Biden has refused since the invasion of Ukraine to deal directly with Russian President Vladimir Putin, who is conspicuously absent from the Bali summit.

The Kremlin cited scheduling issues and has instead sent longtime foreign minister, Sergei Lavrov, who arrived Sunday evening.

Lavrov, 72, denied reports that he was receiving treatment at a Bali hospital, telling Tass news agency that he was in his hotel preparing for the summit. The top diplomat underwent brief health checks on Sunday and Monday, according to an Indonesian health ministry official.

Lavrov's presence has thrown into question a customary G20 group photo and joint statement, with Russia sure to reject any explicit calls to end its invasion of Ukraine.

Western leaders hope the G20 summit will step up pressure on Russia to renew a UN-backed deal expiring Saturday to allow grain shipments from Ukraine, a major food exporter to the developing world.

China, despite rhetorical support for Russia, has not supplied weapons for the war in Ukraine, with Moscow obliged to rely on Iran and North Korea, according to US officials.

"I think there is undeniably some discomfort in Beijing about what we've seen in terms of reckless rhetoric and activity on the part of Russia," a US official said hours before the Xi-Biden talks.

Ukrainian president Volodymyr Zelensky -- invited as a compromise with host Indonesia -- will address the summit by videoconference, a day after a triumphant visit to Kherson, a key city taken back from Russian forces.