China drew first blood in their battle with Japan for Asian Games swimming supremacy, winning three golds to Japan's two on a sultry opening finals night at the Thammasat University aquatics complex. The mainlanders - hoping to take the lion's share of the 32 golds on offer in Bangkok - got off to a flying start when Shan Ying swept to gold in the women's 100 metres before Zeng Qiliang powered home to finish first in the men's 100m breaststroke. China sealed their gilt-edged evening with a typically dominant performance in the women's 4?200m freestyle relay, with the mainland's quartet finishing a full four seconds ahead of the second-placed Japanese. But China's hopes of a clean sweep had been shattered earlier in the evening in the women's 400m individual medley as world record holder and reigning world champion Chen Yan slumped to third behind teammate Wu Yanyan in second and Japan's Yasuko Tajima, who took gold. Chen, who smashed the world record for the distance at last year's All China Games in Shanghai when she clocked four minutes and 34.79 seconds, was close to 13 seconds off her mark as she trailed in in 4:47.34. A Chinese swimming official later declined to comment on the dip in Chen's form when approached by a reporter. None of last night's medal winners held press conferences as dozens of journalists besieged organisers with complaints over facilities. The US$38-million complex has been hit by problems in the buildup to the Games, with insects swarming into the pool the most high-profile problem. Last night, although clouds of bugs swarmed in the stadium to the irritation of spectators, the swimmers appeared unconcerned. As expected, Hong Kong's challenge ended in the morning's heats, with only the women's 4 ? 200m freestyle team representing the SAR in the straight final. The team of Pang Shuk-mui, Pamela Tung Xueming, Robyn Lamsam and Sherry Tsai Hiu-wai finished seventh. In the individual events, Sherry Tsai Hiu-wai was narrowly edged out of a place in the final of the women's 100m freestyle earlier in the day after a gutsy swim. Tsai was ninth fastest in the pool with South Korea's Lee Bo-eun pipping her by 0.53 seconds for a top-eight place. Tsai gained a measure of consolation by winning last night's B final. In the men's 100m breaststroke, both Kwok Hon-ming and Michael Scott also found the going tough, finishing 13th and 14th fastest in their respective heats overall. In the men's 200m freestyle, US-based Zachary Moffatt finished with a respectable time of 1:56.38, but it was not good enough to earn a final berth.