Microsoft's top executive in China resigned to head the National Basketball Association's operations in the world's most populous country.

Tim Chen will head the NBA's business in the Greater China region, including Hong Kong and Taiwan, beginning Oct. 15, the NBA said in a statement Wednesday, citing Commissioner David Stern. Microsoft said it has begun searching for a replacement.

Chen's departure underscores Microsoft's difficulty hanging on to executives in the world's fastest growing major economy. Since 2002, former China heads have defected to online game company Shanda Interactive Entertainment and News Corp.'s Star Group. In 2005, Microsoft sued Google after the Web-search company lured away Lee Kai-Fu to head its China operations.

"Microsoft is a big name and so their China executives are targets for a lot of companies," said Liu Bin, a technology analyst at Beijing-based research company BDA China. "There are a scarce number of executives that have experience in multinationals and an understanding of the Chinese market."

Chen, who has an MBA from the University of Chicago, was head of Motorola's China operations between 2001 and 2003, the NBA said.

Microsoft said it named Ya-Qin Zhang as acting chief executive officer of its operations. Zhang is chairman of Microsoft's research and development group in China, the division that Lee Kai-Fu established.

The NBA is targeting China to boost revenue after the popularity of Chinese national Yao Ming of the Houston Rockets, who was the top draft pick in 2002. The Chinese sports ministry says there are 300 million basketball players in the country and it is the most popular sport among youths.

China is the NBA's largest market outside the United States, the league said. About 20 percent of the traffic on its Web site comes from China, where it sells its merchandise to fans through 50,000 outlets.

Information from Reuters is included in this report.