A top Chinese sports official has played down expectations at the London Olympics, saying it will be tough to repeat the medal-table-topping performance of four years ago on home soil. “Based on a study of the past five Games, the host country wins record high medals at their home Olympics, but their medal total drops dramatically at the next edition,” said Cai Zhenhua, vice minister of sports. “Because a number of Olympic and world champions retired after the Beijing Games, a younger generation will form the bulk of the Chinese Olympic legion,” Cai told the state Xinhua news agency. “Some of our young athletes lack international exposure and consistency, so we cannot be very optimistic about their performances,” said Cai, with the Games less than 100 days away.