Heavyweight rivals Park Tae-Hwan and Sun Yang won their heats in the men's 200 metres freestyle on the first day of the Asian Games swimming Sunday but local hero Park looked less than comfortable.

Park, the Games poster boy after whom the Incheon aquatics arena is named, sauntered onto the pool deck looking relaxed in a pair of headphones but left with a wry look after clocking one minute 50.29 seconds, just 0.14 ahead of China's Li Yunqi.

"That wasn't my best swim but it was just the heats," the 2008 Olympic 400m champion told reporters after recording the fourth-fastest time of the morning session. "I will have to swim better tonight and be at my best for the final."

On the evidence of the heats, Sun will be the man to beat after winning his heat with plenty to spare in 1:48.90.

Sun and Park will also clash in the 400m and 1,500m in a triple-header widely hyped as the highlight of the quadrennial Asian Games.

The towering Chinese is the reigning 400m and 1,500m world and Olympic champion, while Park won gold in the 400m at the 2008 Beijing Games.

Japan's medley specialist Kosuke Hagino, a good bet for a medal in Sunday's 200m free, clocked 1:48.99 with team-mate Takeshi Matsuda third fastest in the heats in 1:50.20.

China have dominated the Asian Games swimming in recent years, winning 24 of the 38 golds at Guangzhou in 2010, with Japan finishing a distant second with nine. (Yonhap)