For many, Google Inc seems to have had a hard time in China, as its business has been consistently disrupted by its relationship with the Chinese government.

But the US search engine has established itself since officially opening for business in China in 2005, with a market share that increased about 10 percent during the past four years.

Then Kai-Fu Lee, the superstar chief of Google China operations since 2005, quit the company last month to launch a $115 million fund to finance Chinese technology startups.

Now the US search engine is looking for new ways to tap the world's largest population.

Most agree that the major challenge for Google has been its relationship with the Chinese government, which has been wary of the growth of the Internet search engine.

Since Google launched its Chinese-language search engine in 2003, one year earlier than domestic rival Baidu.com, its service has been intermittently stopped or delayed by authorities.

Google offered a compromise in 2005, launching its current Chinese-language service under the supervision of Chinese authorities.

"I think what Google really needs is a China ambassador who can communicate with both Google's headquarters and the Chinese government," said Edward Yu, president of the domestic research firm Analysys International.

Yu said that although Google has many services that are better designed than its domestic rival Baidu, Google will not enjoy great success unless it wins the trust of the Chinese government.

John Liu, the former head of sales for Google China, is taking over Lee's responsibilities in business and operations divisions. The company also appointed Boon-Lock Yeo, director of Google's Shanghai engineering office, to take over Lee's engineering responsibilities.

Danile Alegre, Google's vice president, said Google adopts similar two-chief systems in most countries.

"When we were first in China, there were so many things to do, so we needed to find one person to represent Google," he said. "And now, we have the chance to get back to a system that works well in markets elsewhere."

Under the leadership of Lee, who was born in China's Taiwan province and studied in the United States, Google established an elite engineering team in China and released new services such as Music Search and Map Search that became popular among Chinese users.

Google's market share on the mainland rose to 27.8 percent last year from 16.1 percent in 2006, according to Analysys International, while Baidu's share grew to 62.2 percent from 53.3 percent.

As one of the more prominent figures in the Chinese Internet sector, Lee also is popular among Chinese college students. His personal blog is widely followed, and he runs a popular website (www.kaifulee.com) designed to help young Chinese people achieve information technology (IT) careers .

Liu said Lee's departure will not have a great impact on the company, but that Google's attractiveness to college student might fade in the wake of Lee's departure.