SHANGHAI - Meetings between leaders of the United States and China have mostly been dour, orchestrated affairs conducted by teams of men in dark suits.
But China's new President Xi Jinping and US President Barack Obama are shedding the script and neckties for their first summit, an informal get-together this week in the California desert.
Since President Richard Nixon's visit to Beijing in 1972, which broke decades of estrangement between the two countries, the summits have been carefully plotted rituals.
One exception has been a visit by President Jiang Zemin to George W. Bush's ranch in Texas in 2002, but it was only for a few hours.
But an informal setting suits both Obama and Xi and the payoff could be huge if they can build a rapport that brings the world's top two economies closer.
Nevertheless, the short-sleeves meeting is shaping up as anything but relaxing - the two sides have to overcome differences on cyber-security, the South China Sea, North Korea and other issues.
"You'd never imagine that other Chinese leaders would agree to such a kind of meeting," said Ruan Zongze, a former Chinese diplomat, of the summit at a lush private estate called"Sunnylands" in the resort community of Rancho Mirage.
"That's a very important message to the Americans: That we'd like to engage, we'd like to have discussions with them. I think Xi is more accessible and this will be a very good opportunity for Xi and Obama to build a better personal relationship," said Ruan, vice president of the China Institute of International Studies, a think-tank linked to the Chinese Foreign Ministry.
Such an informal setting would appear to play more to Obama's strengths.
But if any Chinese leader has a shot at matching Obama in the charm stakes, it's Xi, who took over from the notoriously wooden Hu Jintao as Communist Party leader late last year and as president in March.
According to US officials at the time, Hu declined Bush's offer in 2006 for a laid-back meeting at his ranch home, something many other foreign leaders would have welcomed. Hu preferred the decorum of the White House.
Unlike the baby-kissing politicians of the West, China's Communist Party works hard to keep its top leaders from appearing too human - to the extent that for many, even their official birth dates and the names of their children are regarded as a state secret.
Xi, though, has cultivated a casual image, appearing relaxed in public, occasionally speaking off the cuff and making sure there is less pomp when Chinese officials make trips.
On a visit to the city of Shenzhen last year he chose to be ferried around in a minibus rather than a presidential sedan and broke from script to shake hands with locals, almost unheard of by a senior Chinese leader.
Xi's glamorous wife, Peng Liyuan, will share the limelight, much as Michelle Obama does with her husband. Peng, a famous singer, made a splash travelling with Xi to Russia and Africa in March, breaking the mould of Chinese first wives who have traditionally kept out of the limelight.
The June 7-8 summit meetings will be held at Sunnylands, the 1960s-era winter home of philanthropists Walter and Leonore Annenberg, which they hoped one day would become a 'Camp David of the West'.
The schedule is designed for Xi and Obama to have time to get to know each other, US government sources said. Between group meetings the two are expected to have some one-on-one time among the manicured gardens and walking paths at the estate.
"The (new) Chinese leadership seemed to be off to a rather quick start... We calculated that, and interestingly, the Chinese agreed to do something we hadn't done before, which was to create an informal menu that would allow the leaders to talk - and actually to really talk - and be able to do so over the span of two different days," a senior US official said.
"This meeting should allow them to talk about the issues in a way that diverts from the tradition of dueling talking points, where a Chinese leader reads from a script and an American leader responds on fairly predictable lines."
Nevertheless, the official said it would be wrong to look at the summit as if it were "a slot machine and at the end it's going to pay out in tokens of deliverables".
"What we are doing and what the Chinese are doing is to try for greater convergence and also to try to avert some of the more problematic and more confrontational possibilities in the relationship."
Delegates to a regional security meeting in Singapore at the weekend also said the Chinese military officials there came ready to talk, with a new sense of openness and charm.
Xi and Obama are well matched for a no-neckties business meeting, said Shi Yinhong, director of the Centre for American Studies at Beijing's Renmin University, who has advised the government on relations with the United States.
"Obama is a great performer. He can be relaxed, but also hard-nosed. Xi is the same," said Shi.
For much of his first term, Obama put less emphasis on forging close personal bonds with other world leaders than his back-slapping predecessor, Bush.
Bush often invited leaders to his ranch or the Camp David presidential retreat for extra face time.
Obama has rarely gone that far, but he has shown an ability to turn on the charm when he sees fit, as he did in his March visit to Israel where he struck a chummier tone with Prime Minister Benjamin Netanyahu.
The California meeting was tacked on to the tail end of Xi's state visits to Mexico, Costa Rica and Trinidad. Both Beijing and Washington saw value in the rendezvous even though in the second half of the year, Obama and Xi will have at least three chances to meet, starting with September's G20 meeting.
"By meeting early, by chatting early, by reaching a level of trust early, things will go smoothly this year and relations between the two countries will be more stable," said Shen Dingli, Vice Dean of the Institute of International Affairs at Shanghai's Fudan University.
"The results may be better because of the fact that they are taking off their ties and dispensing of ceremony. It's a little more free because it's not tied up in high diplomatic protocol."
Past Chinese leaders have used the formality of their meetings with US presidents to tell domestic audiences that their Communist Party-run government is honoured by the world's sole superpower. But Xi is also likely to spin the informality of sunny California to his advantage.
"Sure, a formal state dinner would be wonderful," said Renmin University's Shi.
"But the Chinese leaders will be able to describe these informal talks as a way to prove that Sino-US relations are more intimate."