Sun Yang's only opponent in the 1,500m freestyle final is his own world record.

Spearheading the 1,500m heats in 14 min 34.25 sec - almost three seconds ahead of runner-up Oussama Mellouli of Tunisia - Sun's main competition will be himself in his signature race on Saturday.

The 20-year-old smashed Australian distance swimmer Grant Hackett's decade-long world record at the Shanghai Worlds last year, clocking 14:34.14. Given his impressive performances en route to claiming his first Olympic gold in the men's 400m and the silver in 200m, Sun has almost secured his second gold in 1,500m at his Olympic debut in London.

The only question is: Can he outperform himself to beat his own record?

His winning momentum suggests it's possible.

After shattering defending champion Park Tae-hwan of South Korea to win the 400m in 3:40.14, Sun improved his result at the Shanghai meet by 3.1 seconds and tapped his potential in the last 100 meters, coming up from behind to fly past Park.

He overtook opponents again in the last leg of the 4x200 freestyle relay to lift China from fifth to third in the final, bringing China's men's team to the podium for the first time in the Olympics.

After the demanding final sprint, the exhausted Sun was too tired to celebrate and rested for a long time beside the pool.

But Sun said he's fully recovered.

"I have regained my full strength after a whole day's rest," Sun said on his micro blog on Thursday.

"Please don't worry about my form in the 1,500m final."

If Sun scoops up his second gold medal as expected, he will become the first swimmer to take both the 400m and 1,500m in 32 years. Russian Vladimier Salnikov did it at the 1980 Moscow Games.

Still, Sun has to be wary of the defending champion Mellouli, who just recovered from a shoulder injury and has been showing growing momentum.

"I'm just happy to get the first race in this Olympics," the 28-year-old Tunisian said.

"I had some problems with my shoulder bugging me for the last three years. It seems to be working pretty well this morning. I'm feeling pretty confident for tomorrow."

Sun's rival Park finished the heat in sixth in 14:56.89 but stressed he will do better in the final.

"I am happy with my time, but it's slower than my personal best," Sun said.

"It was an average race."

sunxiaochen@chinadaily.com.cn

(China Daily 08/04/2012 page8)