Sun Yang took China's first-ever men's Olympic gold in the pool with a last-length dash to beat Korea's defending champion Park Taehwan in the 400 meter freestyle final.

Sun, the world champion in the 800 meters and 1,500 meters, trailed Park until the final turn, kicking himself into an unassailable lead and cruising home.

Had he timed his finish better, he might have taken Paul Biedermann's world record of 3 minutes 40.07 seconds, set in Rome in 2009.

He finished five hundredths of a second back, with Park two seconds behind and America's double Olympic champion Peter Vanderkaay another two seconds adrift.