Sun Yang was crowned Olympic swimming champion in the 400 metres freestyle as he continued to leave an indelible mark on the global stage at the Aquatics Centre.

The 20-year-old was second over eight lengths at the World Championships in Shanghai last year before producing a sublime 1,500m freestyle in which he lowered Grant Hackett's long-standing world record.

While talk of the Chinese swimmer has focused on how far into uncharted territory he can take the longer event, Sun came to London heading the 400m world rankings.

He qualified fastest from a dramatic morning session which had seen defending champion Park Tae-Hwan disqualified and then reinstated.

South Korean Park was second on Saturday night, with Peter Vanderkaay of the United States third.

Sun's time of three minutes and 40.14 seconds was an Olympic record and the 20-year-old was under world record pace until the final metres when he slipped outside.

It surely cannot be so long before he, or another swimmer, breaks it but it demonstrates the advantage of performance-enhancing suits at the back end of a race. Paul Biedermann broke the world record in the turbo suit chaos of 2009 but he failed to make it through to the final.

Sun and Park were in a shoot-out with 100m to go but the former took control on the penultimate length, his languid stroke lengthening. Carry touched in seventh in 3:48.62, his qualification for the final "a dream come true" for the Scot who at 30 is the oldest on the team.

Meanhwile, Australia won the gold medal in the women's swimming 4x100 metres freestyle relay final.

Australia won in an Olympic record of 3:33.15 ahead of the Netherlands whose anchor swimmer, Ranomi Kromowidjojo, served notice of her intention in the individual event with an eye-watering 100m of 51.93. The United States were third.