In China Mark Zuckerberg is almost unknown. Now, after pictures of him visiting Beijing's biggest internet company have appeared online, feverish speculation has erupted over whether he could be set to change that by taking his social networking site, Facebook, into the one country that has resisted its charms.
That Mr Zuckerberg is in Beijing this week might alone be enough to trigger rumours as to his intentions – even if it is nominally for a holiday with his girlfriend Priscilla Chan and no other entourage.
But when he was spotted yesterday at the headquarters of Baidu, the giant Chinese search engine company, with its chief executive, Robin Li, the reaction reached a pitch of excitement far beyond what is good for most people's health.
Any alliance was denied by Baidu's spokesman. But there is little doubt that the Chinese market remains a tempting prize for the 26-year-old Mr Zuckerberg. Facebook has been blocked by the Chinese government, denying him access to the country's 300 million regular internet users.
Indeed, Mr Zuckerberg earlier this year revealed he is studying Mandarin Chinese and described his appetite for conquering the country of 1.6 billion people at a conference in California: "It's kind of a personal challenge this year, I'm taking an hour a day and I'm learning Chinese.
"I'm trying to understand the language, the culture, the mindset – it's just such an important part of the world. How can you connect the whole world if you leave out a billion-six people?"