MICHAEL Chang will become a tennis missionary in Beijing in October - and hopes to lead China out of the international wilderness. Chang, the 21-year-old world number nine from the United States, announced yesterday he would be playing in the Association of Tennis Professionals (ATP) Tour Salem Open in Beijing from October 18-24 rather than the Marlboro Championships exhibition tournament in Hongkong the same week. Before boarding a San Francisco-bound flight out of the territory, Chang said: ''The unfortunate thing about the whole situation is that they fall in the same week. That particularly hurts me because I would love to have played in both. ''Hopefully next year or a couple of years down the road things will change.'' Chang has played in two exhibition matches in Beijing but feels the official ranking tournament can spark major interest. ''I read a newspaper article this morning which said only 100,000 people play tennis in China and I found that very frustrating. You can get more than that back home in Orange County. ''I think it's a great sport for people of all ages to play. I started at six or seven and people are still playing at 90. It's good exercise and you get to meet people and make new friends. ''I really think tennis can take a boom in China and this tournament can be a great start. ''It will be the first tournament in Beijing and it's a great opportunity for me to be part of the event. With tennis picking up in the Asia region I would love China to be part of it. ''Money plays a role in certain circumstances but it was not a major issue in my decision. I feel it is a great opportunity for me to be there for a week and for the Chinese people to see the players they have watched on television in person.''