Tajima, who could only manage a 400m IM bronze medal at January's World Championships, turned the tables on China's powerful medley duo of Chen and Wu Yanyan. Tajima established a lead on the opening butterfly leg and never relinqished it, winning in 4:39.92.

Wu, world record holder and world champion in the 200m Medley, emerged with the silver in 4:46.74, with Chen taking bronze in 4:47.34.

Yosuke Ichikawa gave Japan a second gold, edging home favourite Torlarp Sethsothorn in the men's 200m freestyle. Shusuke Ito grabbed another medal for Japan, lifting bronze in 1:52.81. All three powered past early pacesetter Kim Bang-Hyun of Korea, who led at 50M, 100M and 150m only to be shut out of the medals in fourth.

The Japanese, bested in the swimming gold tally 25-5 by drug-tainted China at Hiroshima four years ago,have been widely predicted to topple the Chinese from their perch. But Shan Ying and Zeng Qiliang gave China gold in the first two finals.

Shan Ying defended the women's 100m freestyle title she won in Hiroshima four years ago, despite a lacklustre qualifying performance that saw her swimming out in lane one. World championship silver medallist Zeng Qiliang gave China its second gold, surging past Japan's Akira Hayashi to win the 100m breaststroke in 1:02.32s. Hayashi, who won this event in the 1994 Asian Games, settled for silver this time in 1:02.55. Malaysia's Elvin Chia took bronze in 1:03.09.

After the day's four individual events Japan and China had two golds apiece, but China edged ahead in the tally with an easy victory in the women's 4x 200m freestyle relay, ahead of Japan and Taiwan.