DOHA (AFP) -- Mighty China dominated Asian Games swimming on Saturday by clinching five out of six gold medals and delivering a heavy blow to Japanese pride in the process.

China's women swept all four finals while China and Japan split a men's gold each.

Wu Ping, China's 19-year-old defending champion, was never expected to trouble Japan's top two, Ryuichi Shinata and Takeshi Matsuda, in the 200m butterfly.

But after lying back in third place for three laps, he surged past leader Shibata and Matsuda over the last 50 meters to win in 1min 54.91sec. Matsuda took the silver in 1:55.49 with Shibata third in 1:56.44.

"We studied videos of these Japanese swimmers and we found their weak point," said Wu. "The Japanese slow down in the last leg, so I knew I had to speed up then."

China's women won the first gold of the night through Pang Jiaying, the Olympic relay silver medalist, in the 200m freestyle in a time of 1:59.26.

Compatriot Yang Yu, the 21-year-old defending champion, took silver in 2:00.73, while Maki Mita of Japan claimed bronze in 2:00.78.

Victory was sweat for Pang, 21, who beat Yang at the East Asian Games last year over the same distance.

Defending champion Zhou Yafei won the women's 100m butterfly in 58.39sec, just outside the Asian record.

Zhou, 22, already one of the older performers and feeling the pressure from younger team-mates, beat compatriot Xu Yanwei, who took silver in 58.73 and Li Tao of Singapore, third in 58.96.

A bad night for Japan extended to Yuko Nakanishi, who won the silver four years ago in Busan but was fifth here.

However, she is expected to mount a stronger challenge for gold on Monday in the 200m in which she won the bronze at the Athens Olympics.

Asian champion Ji Liping won gold in the 50m freestyle, the first time the distance has been raced at the Asian Games, in 31.52sec. She held off Japan's Asami Kitagawa, who finished second, while rising star Wang Qun, only 13, claimed the bronze for China.

China's all-conquering women went on to win the 4x100m medley relay in 4:04.22 from Japan, second in 4:05.14 and South Korea, winning the bronze in 4:09.22.

Hidemasa Sano won Japan's only gold of the opening night in the pool.

He clinched the men's 400m individual medley title in 4:16.18. Compatriot Shinya Taniguchi came second with Han Kyu Chul of South Korea in third.