China's Sun Yang reacts after he won gold in the men's 1500m freestyle final in world record time during the London 2012 Olympic Games at the Aquatics Centre August 4, 2012. [Photo / Agencies]

LONDON -- China's emerging standout Sun Yang wiped more than three seconds off the previous world record he set to win 1,500 freestyle gold at London Games on Saturday, turning over a new chapter to dominate the world's long course swimming.

Sun, world record holder of the event, asserted supremacy in the final as he led all the way to touch in 14:31.02, edging over silver medalist with an unbelievable eight seconds.

He broke his the world record of 14:34.14 which he made at the 2011 Shanghai World Championships.

Sun, fastest qualifier for the final, fell off the starting block before the buzzer, but retook his place to lead the race.

Canadian swimmer Ryan Cochrane, bronze medalist of Beijing Games, trailed Sun in the race but was dropped by nearly half lap to pocket a silver medal in 14:39.63.

Tusian defending Olympic champion Oussama Mellouli, the first male African swimmer to win an individual Olympic gold from Beijing Games, settled for a bronze with nine seconds behind Sun.

South Korean Park Tae Hwan tasted his second defeat by Sun in London following the 400m freestyle event and finished fourth.

After sprinting to the wall first, Sun seemed astonished by his record on the scoreboard, and couldnot help bursting in tears in pool.

He punched the water in delight and let out an extended bellow.

"There were too much roars in the stands. When I fell off the block I was thinking if I was disqualified by a false start," said Sun.

"God bless! I was not. I made it," said an excited 20-year-old.

"My brain draws a blank after that (retake the place). I just told myself to do my best, not to load too much pressure," Sun said.

It is the second gold medal Sun has taken from London Games, making himself the first Chinese male swimmer to clinch an Olympic gold medal. Sun also took a silver and a bronze, adding to his tally of four brilliant Olympic medals.