Park Tae-hwan of the ROK celebrates with Sun Yang of China at the end of the men's 400m freestyle final on Tuesday. Park won gold and Sun the silver. Peter Parks / Agence France-Presse

After claiming his second swimming gold medal at the Guangzhou Asian Games, the Republic of Korea's Park Tae-hwan is eyeing a hat-trick.

"I'm very happy to win the race today. I want to raise my physical condition to come up with more victories in the days ahead," said Park, who edged China's Sun Yang and Zhang Lin to win the men's 400m freestyle on Tuesday.

The result has temporarily cooled a debate in the long rivalry between Park and world champion Zhang over who is the more dominant.

The defending champion said he only had to compete against himself.

"I was very nervous at the beginning because this was a race against myself," said Park.

Tuesday's win mirrored his victory over the Chinese duo in the men's 200m freestyle final on Sunday, and set an Asian record in the process.

Sun claimed the silver medal in that race, while Zhang only managed a fourth-place finish.

"I'm very satisfied with today's performance," said Park, who became the ROK's first Olympic medalist in swimming by winning the gold at 400m at the 2008 Beijing Games.

"I'm looking forward to doing even better in future events," he said.

For Wednesday's 100m race, Park is cautious about predicting a third gold.

"The 100m race will be a tough one; my only goal is to have the best competition with the world's best athletes," he said.

On Tuesday, Park led all the way and touched the wall in three minutes and 41.53 seconds - only 0.18 behind Zhang's Asian record.

The 19-year-old Sun took silver in 3:42.47, followed by Asian record holder Zhang in 3:49.15.

In losing to Park in his second individual event at the Guangzhou Games, Zhang again failed to gain the upper hand on the Korean, who defeated him three times in freestyle events at the 2006 Doha Asian Games.

The men's 800m freestyle world record holder said he is in his adjustment period and is expecting an improvement in form.

"I know my results in Guangzhou are not satisfactory and I'm not satisfied with it as well," Zhang said.

"But I know which stage I am at right now and I hope I can handle the current difficult situation."

At the Beijing Olympics, Zhang lost to Park by 0.58 seconds in the 400m race, but he still became China's first male Olympic medalist.

The following year he became China's first male world swimming champion and the world record holder by winning the men's 800m at the Worlds in Rome.

"In 2008-09 everything went smoothly for me, but this year I tried some new techniques and some new training methods," said Zhang.

"My coach told me to do more basic training to maintain my form and get fully prepared for next year. I know it has been a difficult year for me, but I can achieve more in the future."

Despite Zhang's failure, host China was still the biggest winner in the pool on Tuesday, claiming five of the seven gold medals up for grabs.

Zhou Jiawei won his second gold in the men's 50m butterfly, while Li Zhesi won the women's 50m freestyle. Ji Liping added another gold in the women's 100m breaststroke.

China also won the relay titles in men's 4x100m freestyle and women's 4x200m freestyle, beating archrival Japan in both.