Presidents Barack Obama and Xi Jinping will seclude themselves in a desert oasis on Friday, for an unusually relaxed US-China summit, called to distil some early personal chemistry.
Allegations of Chinese cyber hacking and espionage, North Korea's nuclear defiance and constant trade niggles between the world's two single largest economies and possible future superpower rivals will dominate the talks.
But Obama also has a wider purpose -- trying to glean the strategic vision of the man who will likely guide rising China through the rest of his own presidency, and deep into the administration of whoever succeeds him.
Xi makes his first trip to the United States as president, months after taking control of the full machinery of the Chinese state, and US-based China watchers see the talks as the most significant Sino-US summit in years.
Obama meanwhile will get a new crack at forging progress in a geopolitical relationship likely to partly define his legacy, and which caused the White House frustration in stilted talks with ex-Chinese president Hu Jintao.
The two leaders had not been expected to meet until the G20 summit in Russia in September -- but both sides, sensing uncertainty seeping into a complicated and often difficult relationship, saw value in an earlier encounter.
The presidents will ditch the formality and convention of normally minutely planned US-China summits, and meet at the sumptuous Annenberg retreat in a sun-scorched corner of California.
"Early in the term of both presidents, we felt that having this type of wide-ranging, informal setting for discussions between the two leaders would allow them to cover the broadest possible agenda," said a US official, speaking on condition of anonymity.
But Obama also wanted to "forge a working relationship that we will be relying on very much in the years to come," the official said.
"The US-China relationship is as important as any bilateral relationship for shaping the trajectory of the global economy and global security in the 21st century."
Obama and Xi are due to meet up on Friday at 0000 GMT before formal talks and a working dinner. They will then meet again on Saturday morning.
The White House is predicting no breakthroughs, in part due to the swiftly organized program and in part because the issues confronting the two leaders are so acute.
Blunt exchanges are expected on cyber security, following a string of reports that China-based operations have stolen huge troves of US military and commercial secrets.
China has signaled that it believes it too is a victim of cyber espionage and will challenge Washington on its own activities.
In a bid to ensure the issue does not overshadow this summit, the two sides have already announced they will hold working group level talks on cyber security in July.
North Korea will also come up, with US officials encouraged at signs that China is becoming impatient with Pyongyang's saber rattling.
Xi will also be interested in hearing Obama explain his signature diplomatic and military pivot to Asia, which has irked China, where some observers have worried it is about containing Beijing's rise.
Obama is under pressure to tackle what US business leaders complain are China's predatory economic policies and the theft of US intellectual property.
There is already speculation in Washington as to the next steps, should Xi and Obama get along.
John Frisbie, president of the US-China Business Council said the talks were 50 percent successful already just for taking place at this early date.
"Depending on how this weekend goes, the next step ... might be an annual presidential summit," he said.
"Many people, ourselves included ... feel this is an important bilateral relationship, one of the most important, if not the most important for each country."
Ahead of the talks, activists and family members of political prisoners incarcerated in Chinese jails called on Obama to make human rights a priority at the talks.
"President Obama should stop the trade-centered diplomacy and instead make it a human rights-centered diplomacy," said Chen Guangcheng, the blind lawyer who escaped house arrest for the US embassy in Beijing last year.
Obama visited China in 2009, and granted Xi's predecessor a state visit in 2011.